Physics study material (1)

!## $%' ( NNNNeeeellllssssoooonnnn RRRRoooolllliiiihhhhllllaaaahhhhllllaaaa
MMMMaaaannnnddddeeeellllaaaa, 18
,1918)

.
! #$%' ()* #+(,- .!/01 234235
67к9. к:;# =; +? @AB A?%Cх
E FG %7: кI 6JKL M0NO к9, ! (7:
@PQ * ER3S @TC,к9 . +? @ABк9
A?%CкM %U VW%3- %M Xк Fк9 YZ[]
27 YA^% V3_ %`ZaI 6J b,#- 0
9 cB;d@e. 20A шgZh#
#Ti;
##j 67к9- Xк. (

! #9 gk9: l(- m7;
:%] A%neFG. +? @ABк9 A?%CкM %Uo Vp%3Qк9, AFn Yк9 6q^I r
YCM !se.
ZA% 11, 1990- 0
9;r
@ * FGl 6q^I r
%t7M

u!/ ([jr!, ш- 6qv/ +? lq
%!/ !l%jr!, %
Yw Uxjr! кyz e . #$F,# #?Y{FiG;r
к|r #шY9
;v6/. Aк9 U
xM lF}G9, Yg~%g @@ 9, YY)9 r;
M€F@e*. l35- 1993- ] 6‚ZaL ? Zƒ„?:х…†‡. Y,ш-
r; $)*+, ! l% gkк9 YZ[] M€FAYˆjкg !/('FG.
‰gŠM[b Z‹[] ?7: @[69, ŒY, шŽ A;
Y(~F7:M .;%~6J #i? к9 .g Yˆ%'!e‘7! r Uкx9~FG ekV{.
PQF ш r; 1990 - 'PQF F/', Aƒ’ L 6qƒ”“ %•–7 Yw
Zƒ„?gY~%]. PQF ш ;r
rк9 .g YFi ]. ##jl#'M
]lJк9 A?%CкM VW%r R3 #к9 r Xк #–кM %FG. #c‘ 9
к|r ƒк9~ E FG
Zƒ sкI , %4I |—’ ˜ g YM 7;/
M€F@Y';6/*. Œ( F™- VF] E!/ M[7 F™- 7
j;к9/ –FG 7к9

M[bM UoFG gk]‘. 6‚ZaL ? Zƒ„?g
%•–7 Y 7;/ M€F@j;RM, 1990- Ž/ VšF #F(~F PQFF/
=]‘ PQF–7 Y ; g; M€F@j;к9.r r
TxZ’ 5, 2013 F›eFG.
r AC Yˆ%' #! %K4#œ? # :х%•ž v!7rFG.

6q^I r y? M€FAYˆjкM C #d:, Ÿ; %` Yg#69
#к35].
G. Sree Kar M.Sc, B.Ed

IIIInnnnddddeeeexxxx
www.cramanji.webnode.com
1111.... HHHHeeeeaaaatttt………………………………………………………………………………………………………………………………………………………………00001111--00004444
2222.... RRRReeeefffflllleeeeccccttttiiiioooonnnn ooooffff LLLLiiiigggghhhhtttt bbbbyyyy DDDDiiiiffffffffeeeerrrreeeennnntttt SSSSuuuurrrrffffaaaacccceeeessss............ 00005555--11110000
3333.... RRRReeeeffffrrrraaaaccccttttiiiioooonnnn ooooffff LLLLiiiigggghhhhtttt aaaatttt PPPPllllaaaannnneeee SSSSuuuurrrrffffaaaacccceeeessss……………………....11111111--11117777
4444.... RRRReeeeffffrrrraaaaccccttttiiiioooonnnn ooooffff LLLLiiiigggghhhhtttt aaaatttt CCCCuuuurrrrvvvveeeedddd SSSSuuuurrrrffffaaaacccceeeessss…………......11118888-22226666
5555.... HHHHuuuummmmaaaannnn EEEEyyyyeeee aaaannnndddd ccccoooolllloooouuuurrrrffffuuuullll WWWWoooorrrrlllldddd………………………………........22227777-33333333
6666.... EEEElllleeeeccccttttrrrriiiicccc CCCCuuuurrrrrrrreeeennnntttt…………………………………………………………………………………………………………......33334444-44442222
7777.... EEEElllleeeeccccttttrrrroooommmmaaaaggggnnnneeeettttiiiissssmmmm………………………………....………………………………………………………………........44443333--55550000

-

1
Chapter -1
Heat
www.cramanji.webnode.com
1. What would be the final temperature of a mixture of 111... WWWhhhaaattt wwwooouuulllddd bbbeee ttthhheee fffiiinnnaaalll ttteeemmmpppeeerrraaatttuuurrreee ooofff aaa mmmiiixxxtttuuurrreee ooofff 55550000gggg ooooffff wwwwaaaatttteeeerrrr aaaatttt 222200000CCCC tttteeeemmmmppppeeeerrrraaaattttuuuurrrreeee aaaannnndddd 55550000gggg ooooffff
wwwwaaaatttteeeerrrr aaaatttt 444400000CCCC tttteeeemmmmppppeeeerrrraaaattttuuuurrrreeee???? ((((AAAASSSS1111))))
SSSSoooolllluuuuttttiiiioooonnnn :- Given m1 = 50g T1= 200C Final temperature , T= ?
m2 = 50 g T2 = 400C
FFFFoooorrrrmmmmuuuullllaaaa :- T =

T =

=

=

= 300C
2222.... EEEExxxxppppllllaaaaiiiinnnn wwwwhhhhyyyy ddddooooggggssss ppppaaaannnntttt dddduuuurrrriiiinnnngggg hhhhooootttt ssssuuuummmmmmmmeeeerrrr ddddaaaayyyyssss uuuussssiiiinnnngggg tttthhhheeee ccccoooonnnncccceeeepppptttt ooooffff eeeevvvvaaaappppoooorrrraaaattttiiiioooonnnn???? ((((AAAASSSS1111))))
1. Dogs pants on hot days because they are trying to cool down just like we sweat on a hot days.
2. So, dogs pant to regulate their body temperature.
3333.... WWWWhhhhyyyy ddddoooo wwwweeee ggggeeeetttt ddddeeeewwww oooonnnn tttthhhheeee ssssuuuurrrrffffaaaacccceeee ooooffff aaaa ccccoooolllldddd ssssoooofffftttt ddddrrrriiiinnnnkkkk bbbboooottttttttlllleeee kkkkeeeepppptttt iiiinnnn ooooppppeeeennnn aaaaiiiirrrr???? ((((AAAASSSS1111))))
1. When a cold soft drink bottle kept in open air, bottle surface absorb the heat from the
surrounding air.
2. So, outer surface of the molecules get cooled, thus the water droplets are formed.
4444.... WWWWrrrriiiitttteeee tttthhhheeee ddddiiiiffffffffeeeerrrreeeennnncccceeeessss bbbbeeeettttwwwweeeeeeeennnn eeeevvvvaaaappppoooorrrraaaattttiiiioooonnnn aaaannnndddd bbbbooooiiiilllliiiinnnngggg???? ((((AAAASSSS1111))))
Evaporation takes place at any temperature, while boiling occurs at a definite temperature(1000C).
5555.... DDDDooooeeeessss tttthhhheeee ssssuuuurrrrrrrroooouuuunnnnddddiiiinnnngggg aaaaiiiirrrr bbbbeeeeccccoooommmmeeee wwwwaaaarrrrmmmm oooorrrr ccccoooooooollll wwwwhhhheeeennnn vvvvaaaappppoooourrrrssss pppphhhhaaaasssseeee ooooffff HHHH2OOOO ccccoooonnnnddddeeeennnnsssseeeessss???? EEEExxxxppppllllaaaaiiiinnnn????
The surrounds air becomes warm when vapour phase of H2O condenses.
EEEExxxxppppllllaaaannnnaaaattttiiiioooonnnn: - 1.... Heat is transferred from vapour phase of H2O to surrounding air.
2. So, The surrounds air becomes warm when vapour phase of H2O condenses.
6666.... AAAAnnnnsssswwwweeeerrrr tttthhhheeeesssseeee.... ((((AAAASSSS1111))))
aaaa)))) HHHHoooowwww mmmmuuuucccchhhh eeeennnneeeerrrrggggyyyy iiiissss ttttrrrraaaannnnssssffffeeeerrrrrrrreeeedddd wwwwhhhheeeennnn 1111ggggmmmm ooooffff bbbbooooiiiilllliiiinnnngggg wwwwaaaatttteeeerrrr aaaatttt 1111000000000CCCC ccccoooonnnnddddeeeennnnsssseeeessss ttttoooo wwwwaaaatttteeeerrrr aaaatttt 1111000000000CCCC????
540 calories of heat energy is transferred when 1 gm of boiling water at 100o C condenses to water
at 1000 C.
bbbb)))) HHHHoooowwww mmmmuuuucccchhhh eeeennnneeeerrrrggggyyyy iiiissss ttttrrrraaaannnnssssffffeeeerrrrrrrreeeedddd wwwwhhhheeeennnn 1111ggggmmmm ooooffff bbbbooooiiiilllliiiinnnngggg wwwwaaaatttteeeerrrr aaaatttt 1111000000000CCCC ccccoooooooollllssss ttttoooo wwwwaaaatttteeeerrrr aaaatttt 00CCCC????
1. The heat energy transferred when 1 gm of water at 1000 C to become water at 00c on cooling
is 100 calories.
2. Hence, (540+100) calories =640 calories of heat is transferred when 1 gm of boiling water at
1000c cool water at 00C.

2
c) How much energy is transferred when ccc))) HHHooowww mmmuuuccchhh eeennneeerrrgggyyy iiisss tttrrraaannnsssfffeeerrrrrreeeddd wwwhhheeennn 1111ggggmmmm ooooffff wwwwaaaatttteeeerrrr aaaatttt 00000CCCC ffffrrrreeeeeeeezzzzeeeessss ttttoooo iiiicccceeee aaaatttt 00000CCCC????
1 gm of water at 00C releases 80 calories of heat energy when it freezes to ice at 00C.
dddd)))) HHHHoooowwww mmmmuuuucccchhhh eeeennnneeeerrrrggggyyyy iiiissss ttttrrrraaaannnnssssffffeeeerrrrrrrreeeedddd wwwwhhhheeeennnn 1111ggggmmmm ooooffff sssstttteeeeaaaammmm aaaatttt 1111000000000CCCC ttttuuuurrrrnnnnssss ttttoooo iiiicccceeee 00000CCCC????
1. The heat energy transferred when 1 gm of water at 1000 C to become water at 00c on cooling
is 100 calories.
2. Hence, (540+80+100) Calories =720 calories of heat energy is released when 1 gm of steam at
1000C turns to ice at 00C.
7777.... EEEExxxxppppllllaaaaiiiinnnn tttthhhheeee pppprrrroooocccceeeedddduuuurrrreeee ooooffff ffffiiiinnnnddddiiiinnnngggg ssssppppeeeecccciiiiffffiiiicccc hhhheeeeaaaatttt ooooffff ssssoooolllliiiidddd eeeexxxxppppeeeerrrriiiimmmmeeeennnnttttaaaallllllllyyyy.... ((((AAAASSSS1111))))
AAAAiiiimmmm:- To find the specific heat of given solid.
AAAAppppppppaaaarrrraaaattttuuuussss:- Calorimeter, thermometer, stirrer, water, steam heater, wooden box and lead shots.
PPPPrrrroooocccceeeedddduuuurrrreeee:- 1. Let the mass of the calorimeter along with stirrer is ‘ m1’ gm.
2. One third of the volume of the calorimeter is filled with water and its mass is ‘ m2’ gm.
3. The temperature of the calorimeter is noted (T1
0C ).
4. The heated Lead pieces (m3 gm and T2
0C) are quickly transferred in to calorimeter, with
minimum loss of heat.
5. Contents in the calorimeter are stirred and then resultant temperature (T3
0C) is noted .
6. Let the specific heats of the calorimrter, led shots and water are Sc , Sl and Sw respectively.
7. By using the formula we calculate the specific heat of the given solid,
Sl = [m1 Sc + (m2 -m1) Sw (T3- T1)] / (m3 -m2 ) (T2 -T3)
8888.... CCCCoooovvvveeeerrrrtttt 222200000CCCC iiiinnnnttttoooo KKKKeeeellllvvvviiiinnnn ssssccccaaaalllleeee.... ((((AAAASSSS1111))))
Temperature in Kelvin =273 + Temperature in Celsius degrees. =273+20 =293 K
9999.... YYYYoooouuuurrrr ffffrrrriiiieeeennnndddd iiiissss nnnnoooottttaaaabbbblllleeee ttttoooo ddddiiiiffffffffeeeerrrreeeennnnttttiiiiaaaatttteeee bbbbeeeettttwwwweeeeeeeennnn eeeevvvvaaaappppoooorrrraaaattttiiiioooonnnn aaaannnndddd bbbbooooiiiilllliiiinnnngggg.... WWWWhhhhaaaatttt qqqquuuueeeessssttttiiiioooonnnnssss ddddoooo yyyyoooouuuu????
aaaasssskkkk ttttoooo mmmmaaaakkkkeeee hhhhiiiimmmm kkkknnnnoooowwww tttthhhheeee ddddiiiiffffffffeeeerrrreeeennnncccceeeessss bbbbeeeettttwwwweeeeeeeennnn eeeevvvvaaaappppoooorrrraaaattttiiiioooonnnn aaaannnndddd bbbbooooiiiilllliiiinnnngggg???? ((((AAAASSSS2222))))
1. Is boiling temperature of the water is always 1000C?
2. How wet clothes dry without heating?
3. Does boiling depend on the surface on the area of a liquid?
4. Does evaporation depend on the surface area of a liquid?
11110000.... WWWWhhhhaaaatttt hhhhaaaappppppppeeeennnnssss ttttoooo tttthhhheeee wwwwaaaatttteeeerrrr wwwwhhhheeeennnn wwwweeeetttt ccccllllooootttthhhheeeessss ddddrrrryyyy???? ((((AAAASSSS3333))))
When wet clothes are dried, the water in them is escaped as water vapour due to evaporation and
mixes with the air.
11111111.... EEEEqqqquuuuaaaallll aaaammmmoooouuuunnnnttttssss ooooffff wwwwaaaatttteeeerrrr aaaarrrreeee kkkkeeeepppptttt iiiinnnn aaaa ccccaaaapppp aaaannnndddd iiiinnnn aaaa ddddiiiisssshhhh.... WWWWhhhhiiiicccchhhh wwwwiiiillllllll eeeevvvvaaaappppoooorrrraaaatttteeee ffffaaaasssstttteeeerrrr???? WWWWhhhhyyyy???? ((((AAAASSSS3333))))
1. Evaporation depends on the surface area.
2. Hence, the water kept in dish will evaporate faster than the cap.

3
12. Suggest an experiment to prove that rate 111222... SSSuuuggggggeeesssttt aaannn eeexxxpppeeerrriiimmmeeennnttt tttooo ppprrrooovvveee ttthhhaaattt rrraaattteee ooooffff eeeevvvvaaaappppoooorrrraaaattttiiiioooonnnn ooooffff lllliiiiqqqquuuuiiiidddd ddddeeeeppppeeeennnnddddssss oooonnnn iiiittttssss ssssuuuurrrrffffaaaacccceeee aaaarrrreeeeaaaa aaaannnndddd
vvvvaaaappppoooouuuurrrr aaaallllrrrreeeeaaaaddddyyyy pppprrrreeeesssseeeennnntttt iiiinnnn ssssuuuurrrrrrrroooouuuunnnnddddiiiinnnngggg aaaaiiiirrrr.... ((((AAAASSSS3333))))
AAAAiiiimmmm:- To prove that rate of evaporation of liquid depends on its surface area.
AAAAppppppppaaaarrrraaaattttuuuussss:- Two dishes of different surface area and water.
PPPPrrrroooocccceeeedddduuuurrrreeee:- 1. Take a small quantity of water in two dishes separately.
2. Keep the dishes under the fan and switch on the fan.
3. After some time observe the quantity of water in both dishes.
4. It is proved that the dishes contain larger surface area of water is fastly evaporated.
11113333.... PPPPllllaaaacccceeee aaaa PPPPyyyyrrrreeeexxxx ffffuuuunnnnnnnneeeellll wwwwiiiitttthhhh iiiittttssss mmmmoooouuuutttthhhh--ddddoooowwwwnnnn iiiinnnn aaaa ssssaaaauuuucccceeee ppppaaaannnn wwwwiiiitttthhhh ffffuuuullllllll ooooffff wwwwaaaatttteeeerrrr,,,, iiiinnnn ssssuuuucccchhhh aaaa wwwwaaaayyyy tttthhhhaaaatttt tttthhhheeee
sssstttteeeemmmm ttttuuuubbbbeeee ooooffff tttthhhheeee ffffuuuunnnnnnnneeeellll iiiissss aaaabbbboooovvvveeee tttthhhheeee wwwwaaaatttteeeerrrr oooorrrr ppppooooiiiinnnnttttiiiinnnngggg uuuuppppwwwwaaaarrrrdddd iiiinnnnttttoooo aaaaiiiirrrr.... RRRReeeesssstttt tttthhhheeee eeeeddddggggeeee ooooffff tttthhhheeee bbbboooottttttttoooommmm
ppppoooorrrrttttiiiioooonnnn ooooffff tttthhhheeee ffffuuuunnnnnnnneeeellll oooonnnn aaaa nnnnaaaaiiiillll oooorrrr oooonnnn aaaa ccccooooiiiinnnn ssssoooo tttthhhhaaaatttt wwwwaaaatttteeeerrrr ccccaaaannnn ggggeeeetttt uuuunnnnddddeeeerrrr iiiitttt.... PPPPllllaaaacccceeee tttthhhheeee ppppaaaannnn oooonnnn aaaa ssssttttoooovvvveeee aaaannnndddd
hhhheeeeaaaatttt iiiitttt ttttiiiillllllll iiiitttt bbbbeeeeggggiiiinnnnssss ttttoooo bbbbooooiiiillll.... WWWWhhhheeeerrrreeee ddddoooo tttthhhheeee bbbbuuuubbbbbbbblllleeeessss ffffoooorrrrmmmm ffffiiiirrrrsssstttt???? WWWWhhhhyyyy???? CCCCaaaannnn yyyyoooouuuu eeeexxxxppppllllaaaaiiiinnnn hhhhoooowwww aaaa Geeeeyyyysssseeeerrrr
wwwwoooorrrrkkkkssss uuuussssiiiinnnngggg aaaabbbboooovvvveeee eeeexxxxppppeeeerrrriiiieeeennnncccceeee???? ((((AAAASSSS4444))))
1. When a Pyrex funnel with its mouth-down in a in a sauce pan with full of water.
2. Rest the edge of the bottom portion of the funnel on a nail or on a coin so that water can get
3. Place the pan on a stove and heat it till it begins to boil. under it.
4. The bubbles of water come from the top of the funnel.
WWWWoooorrrrkkkkiiiinnnngggg ooooffff GGGGeeeeyyyysssseeeerrrr: - 1. The Geyser works on the principle of electrical energy converted into heat
2. When heat energy increases, the inside pressure of Geyser is increases. energy.
3. So, the bubbles of water will come out from the top portion of the Geyser.
11114444.... CCCCoooolllllllleeeecccctttt tttthhhheeee iiiinnnnffffoooorrrrmmmmaaaattttiiiioooonnnn aaaabbbboooouuuutttt wwwwoooorrrrkkkkiiiinnnngggg ooooffff ggggeeeeyyyysssseeeerrrr aaaannnndddd pppprrrreeeeppppaaaarrrreeee aaaa rrrreeeeppppoooorrrrtttt.... ((((AAAASSSS4444))))
1. A geyser has inner heating element made up of Nichrome.
2. It acts as a thermostat unit to control the temperature by switching off the element, once the
desired temperature has been reached.
3. The resistance of the wire restricts the current flow causing a pressure of electrons and potons
and in turn creates a heat.
11115555.... AAAAssssssssuuuummmmeeee tttthhhhaaaatttt hhhheeeeaaaatttt iiiissss bbbbeeeeiiiinnnngggg ssssuuuupppppppplllliiiieeeedddd ccccoooonnnnttttiiiinnnnuuuuoooouuuussssllllyyyy ttttoooo tttthhhheeee iiiicccceeee aaaatttt --50CCCC.... YYYYoooouuuu kkkknnnnoooowwww tttthhhhaaaatttt iiiicccceeee mmmmeeeellllttttssss aaaatttt 00000CCCC aaaannnndddd
bbbbooooiiiillllssss aaaatttt 1111000000000CCCC.... CCCCoooonnnnttttiiiinnnnuuuueeee tttthhhheeee hhhheeeeaaaattttiiiinnnngggg ttttiiiillllllll iiiitttt ssssttttaaaarrrrttttssss bbbbooooiiiilllliiiinnnngggg.... NNNNooootttteeee tttthhhheeee tttteeeemmmmppppeeeerrrraaaattttuuuurrrreeee ffffoooorrrr eeeevvvveeeerrrryyyy mmmmiiiinnnnuuuutttteeee.... DDDDrrrraaaawwww aaaa
ggggrrrraaaapppphhhh bbbbeeeettttwwwweeeeeeeennnn tttteeeemmmmppppeeeerrrraaaattttuuuurrrreeee aaaannnndddd hhhheeeeaaaatttt uuuussssiiiinnnngggg tttthhhheeee vvvvaaaalllluuuueeeessss yyyyoooouuuu ggggeeeetttt.... WWWWhhhhaaaatttt ddddoooo yyyyoooouuuu uuuunnnnddddeeeerrrrssssttttaaaannnndddd ffffrrrroooommmm tttthhhheeee ggggrrrraaaapppphhhh????
WWWWrrrriiiitttteeee tttthhhheeee ccccoooonnnncccclllluuuussssiiiioooonnnnssss.... ((((AAAASSSS5555))))

4
CCCCoooonnnncccclllluuuussssiiiioooonnnnssss:::: - 1.The temperature remains constant at 00C, till all the ice is converted in to water.
2222.... The temperature remains constant at 1000C, until all the water is converted in to water.
16.... HHHHoooowwww ddddoooo yyyyoooouuuu aaaapppppppprrrreeeecccciiiiaaaatttteeee tttthhhheeee rrrroooolllleeee hhhhiiiigggghhhheeeerrrr ssssppppeeeecccciiiiffffiiiicccc ccccaaaappppaaaacccciiiittttyyyy vvvvaaaalllluuuueeee ooooffff wwwwaaaatttteeeerrrr iiiinnnn ssssttttaaaabbbbiiiilllliiiizzzziiiinnnngggg aaaattttmmmmoooosssspppphhhheeeerrrriiiicccc????
tttteeeemmmmppppeeeerrrraaaattttuuuurrrreeee dddduuuurrrriiiinnnngggg wwwwiiiinnnntttteeeerrrr aaaannnndddd ssssuuuummmmmmmmeeeerrrr sssseeeeaaaassssoooonnnnssss???? ((((AAAASSSS6666))))
1. The sun delivers a large amount of energy to the Earth daily.
2. The water masses on Earth, particularly the oceans, absorb this energy for maintaining a
relatively constant temperature.
3. The oceans behave like heat “store houses” for the earth.
4. Therefore, oceans moderate the surrounding temperature near the equator during winter and
summer season
5. So, I appreciate the role higher specific capacity value of water in stabilizing atmospheric
temperature during winter and summer seasons.
11117777.... SSSSuuuuppppppppoooosssseeee tttthhhhaaaatttt ttttoooo 1111 lllliiiittttrrrreeee ooooffff wwwwaaaatttteeeerrrr iiiissss hhhheeeeaaaatttteeeedddd ffffoooorrrr aaaa cccceeeerrrrttttaaaaiiiinnnn ttttiiiimmmmeeee ttttoooo rrrriiiisssseeee aaaannnndddd iiiittttssss tttteeeemmmmppppeeeerrrraaaattttuuuurrrreeee bbbbyyyy 22220CCCC.... IIIIffff
2222 lllliiiitttteeeerrrr ooooffff wwwwaaaatttteeeerrrr ffffoooorrrr tttthhhheeee ssssaaaammmmeeee ttttiiiimmmmeeee,,,, bbbbyyyy hhhhoooowwww mmmmuuuucccchhhh wwwwiiiillllllll iiiittttssss tttteeeemmmmppppeeeerrrraaaattttuuuurrrreeee rrrriiiisssseeeessss???? ((((AAAASSSS7777))))
SSSSoooolllluuuuttttiiiioooonnnn :- Given m1 = 1Kg ΔT1 = 20C
m2 = 2Kg ΔT2 = ?
FFFFoooorrrrmmmmuuuullllaaaa :-

=

====

ΔT2 = 1oC
18.... WWWWhhhhaaaatttt rrrroooolllleeee ddddooooeeeessss ssssppppeeeecccciiiiffffiiiicccc hhhheeeeaaaatttt ccccaaaappppaaaacccciiiittttyyyy ppppllllaaaayyyy iiiinnnn aaaa wwwwaaaatttteeeerrrrmmmmeeeelllloooonnnn ttttoooo kkkkeeeeeeeepppp iiiitttt ccccoooooooollll ffffoooorrrr lllloooonnnngggg ttttiiiimmmmeeee aaaafffftttteeeerrrr rrrreeeemmmmoooovvvviiiinnnngggg
iiiitttt ffffrrrroooommmm aaaa ffffrrrriiiiddddggggeeee oooonnnn aaaa hhhhooootttt ddddaaaayyyy???? ((((AAAASSSS7777))))
1. Water melon brought out from the refrigerator retains its coolness for a longer time than any
other fruit.
2. Because it contains large percentage of water. (Water has greater specific heat).
19.... IIIIffff yyyyoooouuuu aaaarrrreeee cccchhhhiiiillllllllyyyy oooouuuuttttssssiiiiddddeeee tttthhhheeee sssshhhhoooowwwweeeerrrr ssssttttaaaallllllll,,,, wwwwhhhhyyyy ddddoooo yyyyoooouuuu ffffeeeeeeeellll wwwwaaaarrrrmmmm aaaafffftttteeeerrrr tttthhhheeee bbbbaaaatttthhhh iiiiffff yyyyoooouuuu ssssttttaaaayyyy iiiinnnn
bbbbaaaatttthhhhrrrroooooooommmm???? ((((AAAASSSS7777))))
1. In the bathroom, the number of vapour molecules per unit volume is greater than number of
vapour molecules per unit volume outside the room.
2. When you try to dry yourself with a towel, the vapour molecules surrounding you condense on
your skin and this condensation makes you feel warm.
к

.. ! # $%
WWWWhhhhiiiilllleeee yyyyoooouuuu ccccuuuutttt iiiitttt oooouuuutttt bbbblllluuuunnnnttttllllyyyy ttttrrrreeeeeeeessss bbbbeeeeaaaarrrrssss iiiitttt,,,, wwwwiiiitttthhhh dddduuuueeee ppppaaaattttiiiieeeennnncccceeee-- NNNNeeeewwww sssspppprrrroooouuuuttttssss sssshhhhooooooootttt aaaannnndddd sssshhhhoooouuuutttt,,,, aaaassss aaaa ffffiiiittttttttiiiinnnngggg rrrreeeeppppllllyyyy....

5
CCCChhhhaaaapppptttteeeerrrr --3
RRRReeeefffflllleeeeccccttttiiiioooonnnn ooooffff lllliiiigggghhhhtttt oooonnnn ddddiiiiffffffffeeeerrrreeeennnntttt ssssuuuurrrrffffaaaacccceeeessss
1111.... SSSSttttaaaatttteeee tttthhhheeee llllaaaawwwwssss ooooffff rrrreeeefffflllleeeeccccttttiiiioooonnnn ooooffff lllliiiigggghhhhtttt.... ((((AAAASSSS1111))))
LLLLaaaawwwwssss ooooffff RRRReeeefffflllleeeeccccttttiiiioooonnnn ooooffff LLLLiiiigggghhhhtttt:::: - 1. Light travels in a straight line motion.
2. When light gets reflected from a surface, the angle of incidence is equal to the angle of reflection.
3. The incident ray, reflected ray and normal are lies in a same surface.
2222.... WWWWhhhhyyyy ccccoooonnnnccccaaaavvvveeee aaaannnndddd ccccoooonnnnvvvveeeexxxx mmmmiiiirrrrrrrroooorrrrssss aaaarrrreeee ccccaaaalllllllleeeedddd sssspppphhhheeeerrrriiiiccccaaaallll mmmmiiiirrrrrrrroooorrrrssss???? ((((AAAASSSS1111))))
Convex and concave mirrors contain curved surfaces. So, they are called spherical mirrors.
3333.... HHHHoooowwww ddddoooo yyyyoooouuuu ffffiiiinnnndddd tttthhhheeee ffffooooccccaaaallll lllleeeennnnggggtttthhhh ooooffff aaaa ccccoooonnnnccccaaaavvvveeee mmmmiiiirrrrrrrroooorrrr???? ((((AAAASSSS1111))))
1. The reflected rays on the concave mirror are converging at a point.
2. This point is called Focus or focal point (F) of the concave mirror.
3. The distance between the pole and focal point is called its focal length.
4444.... WWWWhhhheeeerrrreeee wwwwiiiillllllll tttthhhheeee iiiimmmmaaaaggggeeee ffffoooorrrrmmmm wwwwhhhheeeennnn wwwweeee ppppllllaaaacccceeee aaaannnn oooobbbbjjjjeeeecccctttt,,,, oooonnnn tttthhhheeee pppprrrriiiinnnncccciiiippppaaaallll aaaaxxxxiiiissss ooooffff aaaa ccccoooonnnnccccaaaavvvveeee mmmmiiiirrrrrrrroooorrrr aaaatttt aaaa
ppppooooiiiinnnntttt bbbbeeeettttwwwweeeeeeeennnn ffffooooccccuuuussss aaaannnndddd cccceeeennnnttttrrrreeee ooooffff ccccuuuurrrrvvvvaaaattttuuuurrrreeee???? ((((AAAASSSS1111))))
When we place an object, on the principal axis of a concave mirror at a point between focus and
centre of curvature the image is formed on beyond the center of curvature.
6666.... SSSSttttaaaatttteeee tttthhhheeee ddddiiiiffffffffeeeerrrreeeennnncccceeeessss bbbbeeeettttwwwweeeeeeeennnn ccccoooonnnnvvvveeeexxxx aaaannnndddd ccccoooonnnnccccaaaavvvveeee mmmmiiiirrrrrrrroooorrrrssss.... ((((AAAASSSS1111))))
CCCCoooonnnnccccaaaavvvveeee mmmmiiiirrrrrrrroooorrrr CCCCoooonnnnvvvveeeexxxx mmmmiiiirrrrrrrroooorrrr
1.The surface of the concave mirror is curved
In wards.
1.The surface of the convex mirror is bulged
Out wards.
2. It reflected real and inverted images. 2. It reflected virtual images.
3. Focal point is formed infront of the mirror. 3.Focal point is formed behind the mirror.
7.... DDDDiiiissssttttiiiinnnngggguuuuiiiisssshhhh bbbbeeeettttwwwweeeeeeeennnn rrrreeeeaaaallll aaaannnndddd vvvviiiirrrrttttuuuuaaaallll iiiimmmmaaaaggggeeee???? ((((AAAASSSS1111))))
RRRReeeeaaaallll iiiimmmmaaaaggggeeee VVVViiiirrrrttttuuuuaaaallll iiiimmmmaaaaggggeeee
1. Real image can be caught on a screen. 1. Virtual image cannot be caught on a screen.
2. These are formed due to converge of rays. 2. These are formed due to diverging of rays.
3. These are always inverted. 3. These are always erect.

6
8. How do you get a virtual image using ... HHHooowww dddooo yyyooouuu gggeeettt aaa vvviiirrrtttuuuaaalll iiimmmaaagggeee uuusssiiinnnggg aaaa ccccoooonnnnccccaaaavvvveeee mmmmiiiirrrrrrrroooorrrr???? ((((AAAASSSS1111))))
If the object is placed in between the pole and focal
point on a concave mirror then virtual images are formed.
9.... WWWWhhhhaaaatttt ddddoooo yyyyoooouuuu kkkknnnnoooowwww aaaabbbboooouuuutttt tttthhhheeee tttteeeerrrrmmmmssss ggggiiiivvvveeeennnn bbbbeeeelllloooowwww rrrreeeellllaaaatttteeeedddd ttttoooo tttthhhheeee sssspppphhhheeeerrrriiiiccccaaaallll mmmmiiiirrrrrrrroooorrrrssss???? ((((AAAASSSS1111))))
aaaa)))) PPPPoooolllleeee bbbb)))) CCCCeeeennnnttttrrrreeee ooooffff ccccuuuurrrrvvvvaaaattttuuuurrrreeee cccc)))) FFFFooooccccuuuussss dddd)))) RRRRaaaaddddiiiiuuuussss ooooffff ccccuuuurrrrvvvvaaaattttuuuurrrreeee eeee)))) FFFFooooccccaaaallll lllleeeennnnggggtttthhhh ffff)))) PPPPrrrriiiinnnncccciiiippppaaaallll aaaaxxxxiiiissss
gggg)))) OOOObbbbjjjjeeeecccctttt ddddiiiissssttttaaaannnncccceeee hhhh)))) IIIImmmmaaaaggggeeee ddddiiiissssttttaaaannnncccceeee iiii)))) MMMMaaaaggggnnnniiiiffffiiiiccccaaaattttiiiioooonnnn.
aaaa)))) PPPPoooolllleeee:::: - The midpoint (Geometrical centre) of the mirror is called pole (P) of the mirror.
bbbb)))) CCCCeeeennnnttttrrrreeee ooooffff ccccuuuurrrrvvvvaaaattttuuuurrrreeee:::: - All normals of concave mirror will converge towards a point. This point is
called centre of curvature(C) of the mirror.
cccc)))) FFFFooooccccuuuussss:::: - All the reflected ray of concave mirror is intersecting at one point on the principle axis
is called focus or focal point (F).
dddd)))) RRRRaaaaddddiiiiuuuussss ooooffff ccccuuuurrrrvvvvaaaattttuuuurrrreeee:::: - The distance between Pole and Center of curvature is radius of curvature
((((RRRR)))) of the mirror.
eeee)))) FFFFooooccccaaaallll lllleeeennnnggggtttthhhh:::: - The distance between pole and focal point of a mirror is called focal length (f).
ffff)))) PPPPrrrriiiinnnncccciiiippppaaaallll aaaaxxxxiiiis:::: - The horizontal line which passes through the centre of curvature and pole is
called central axis or principal axis of the mirror.
gggg)))) OOOObbbbjjjjeeeecccctttt ddddiiiissssttttaaaannnncccceeee:::: - The distance between the pole of a mirror and object is called object distance.
hhhh)))) IIIImmmmaaaaggggeeee ddddiiiissssttttaaaannnncccceeee:::: - The distance between the pole of a mirror and image is called image distance.
iiii)))) MMMMaaaaggggnnnniiiiffffiiiiccccaaaattttiiiioooonnnn:::: - m =

(

)
(or) m= -

()

()
11110000.... WWWWrrrriiiitttteeee tttthhhheeee rrrruuuulllleeeessss mmmmeeeennnnttttiiiioooonnnneeeedddd ffffoooorrrr ssssiiiiggggnnnn ccccoooonnnnvvvveeeennnnttttiiiioooonnnn.... ((((AAAASSSS1111))))
RRRRuuuulllleeeessss mmmmeeeennnnttttiiiioooonnnneeeedddd ffffoooorrrr ssssiiiiggggnnnn ccccoooonnnnvvvveeeennnnttttiiiioooonnnn:::: - 1. All distances should be measured from the pole.
2. The distances measured in the direction of incident light, to be taken as positive.
3. The distances measured in the opposite direction of incident light, to be taken as negative.
11111111.... TTTThhhheeee mmmmaaaaggggnnnniiiiffffiiiiccccaaaattttiiiioooonnnn ooooffff aaaa ppppllllaaaannnneeee mmmmiiiirrrrrrrroooorrrr iiiissss ++++1111.... WWWWhhhhaaaatttt yyyyoooouuuu aaaarrrreeee oooobbbbsssseeeerrrrvvvviiiinnnngggg ffffrrrroooommmm tttthhhhiiiissss vvvvaaaalllluuuueeee????
The magnification of a plane mirror is +1 means both object and images are lie on same plane.

7
12. Imagine that spherical mirrors are not known to human being, guess the 111222... IIImmmaaagggiiinnneee ttthhhaaattt sssppphhheeerrriiicccaaalll mmmiiirrrrrrooorrrsss aaarrreee nnnooottt kkknnnooowwwnnn tttooo hhhuuummmaaannn bbbeeeiiinnnggg,,, ggguuueeessssss ttthhheee ccccoooonnnnsssseeeeqqqquuuueeeennnncccceeeessss.... ((((AAAASSSS2222))))
1. It would be unsafe to drive vehicles, especially in the night.
2. Dentist cannot analyze the problems in our teeth.
3. Many large telescopes to observe the universe will not possible.
13.... BBBByyyy oooobbbbsssseeeerrrrvvvviiiinnnngggg sssstttteeeeeeeellll vvvveeeesssssssseeeellllssss aaaannnndddd ddddiiiiffffffffeeeerrrreeeennnntttt iiiimmmmaaaaggggeeeessss iiiinnnn tttthhhheeeemmmm;;;; SSSSuuuurrrryyyyaaaa,,,, aaaa tttthhhhiiiirrrrdddd ccccllllaaaassssssss ssssttttuuuuddddeeeennnntttt aaaasssskkkkeeeedddd ssssoooommmmeeee
qqqquuuueeeessssttttiiiioooonnnnssss hhhhiiiissss eeeellllddddeeeerrrr ssssiiiisssstttteeeerrrr VVVViiiiddddyyyyaaaa.... WWWWhhhhaaaatttt mmmmaaaayyyy bbbbeeee tttthhhhoooosssseeee qqqquuuueeeessssttttiiiioooonnnnssss???? ((((AAAASSSS2222))))
1. Why our image is reduced in some steel vessels?
2. Why our image is enlarged in some steel vessels?
3. Why we are not observing the clear image in a steel vessel like a mirror?
14.... HHHHoooowwww ddddoooo yyyyoooouuuu vvvveeeerrrriiiiffffyyyy tttthhhheeee 1111sssstttt llllaaaawwww ooooffff rrrreeeefffflllleeeeccccttttiiiioooonnnn ooooffff lllliiiigggghhhhtttt wwwwiiiitttthhhh aaaannnn eeeexxxxppppeeeerrrriiiimmmmeeeennnntttt???? ((((AAAASSSS3333))))
AAAAiiiimmmm:- Verification of first law of reflection of light.
RRRReeeeqqqquuuuiiiirrrreeeedddd mmmmaaaatttteeeerrrriiiiaaaallll:- Mirror strip, drawing board, white paper, pins, clamps scale and pencil.
PPPPrrrroooocccceeeedddduuuurrrreeee:- 1. Take a drawing board and fix a white paper on it with the help of clamps.
2. Draw a straight line PQ making certain angle and find its reflection PI and QI.
3. Join R, S and O as shown in the figure. Measure the angle between RS and ON.
4. You will find that angle of incidence = angle of reflection.
5. Hence first law is verified.
15.... HHHHoooowwww ddddoooo yyyyoooouuuu vvvveeeerrrriiiiffffyyyy tttthhhheeee 2222nnnndddd llllaaaawwww ooooffff rrrreeeefffflllleeeeccccttttiiiioooonnnn ooooffff lllliiiigggghhhhtttt wwwwiiiitttthhhh aaaannnn eeeexxxxppppeeeerrrriiiimmmmeeeennnntttt???? ((((AAAASSSS3333))))
AAAAiiiimmmm:-Verification of second law of reflection of light.
RRRReeeeqqqquuuuiiiirrrreeeedddd mmmmaaaatttteeeerrrriiiiaaaallll:- mirror strip, drawing board, white paper, pins, clamps scale and pencil.
PPPPrrrroooocccceeeedddduuuurrrreeee:- 1. Take a drawing board and fix a white paper on it with the help of clamps.
3. Join R, S and O as shown in the figure.
4. We will find the incident ray PO, The reflected ray RS and normal ON are lying in
the same surface.
5. Hence second law is verified.
NNNNooootttteeee:::: -- DDDDrrrraaaawwww tttthhhheeee ssssaaaammmmeeee ddddiiiiaaaaggggrrrraaaammmm ooooffff qqqquuuueeeessssttttiiiioooonnnn nnnnuuuummmmbbbbeeeerrrr 11114444 ....

8
16. What do you infer from the experiment which you did with concave mirror ... WWWhhhaaattt dddooo yyyooouuu iiinnnfffeeerrr fffrrrooommm ttthhheee eeexxxpppeeerrriiimmmeeennnttt wwwhhhiiiccchhh yyyooouuu dddiiiddd wwwiiittthhh cccooonnncccaaavvveee mmmiiirrrrrrooorrr aaaannnndddd mmmmeeeeaaaassssuuuurrrreeeedddd tttthhhheeee
ddddiiiissssttttaaaannnncccceeee ooooffff oooobbbbjjjjeeeecccctttt aaaannnndddd ddddiiiissssttttaaaannnncccceeee ooooffff iiiimmmmaaaaggggeeee???? ((((AAAASSSS3333))))
PPPPoooossssiiiittttiiiioooonnnn ooooffff tttthhhheeee
ccccaaaannnnddddlllleeee ((((oooobbbbjjjjeeeecccctttt))))
PPPPoooossssiiiittttiiiioooonnnn ooooffff
tttthhhheeee iiiimmmmaaaaggggeeee
BBBBiiiiggggggggeeeerrrr////ssssmmmmaaaalllllllleeeerrrr
tttthhhhaaaannnn oooobbbbjjjjeeeecccctttt
IIIInnnnvvvveeeerrrrtttteeeedddd oooorrrr
eeeerrrreeeecccctttteeeedddd
RRRReeeeaaaallll oooorrrr
vvvviiiirrrrttttuuuuaaaallll
Between mirror F Behind the mirror Bigger Erected Virtual
On focal point At infinity Bigger Inverted Real
Between F and C Beyond C Bigger Inverted Real
On centre of
On C Same size Inverted Real
curvature
Beyond C Between F and C Smaller Inverted Real
17.... FFFFiiiinnnndddd tttthhhheeee ppppllllaaaannnneeee ooooffff tttthhhheeee rrrreeeefffflllleeeeccccttttiiiioooonnnn eeeexxxxppppeeeerrrriiiimmmmeeeennnnttttaaaallllllllyyyy ffffoooorrrr tttthhhheeee iiiinnnncccciiiiddddeeeennnntttt rrrraaaayyyy wwwwhhhhiiiicccchhhh ppppaaaasssssssseeeessss tttthhhhrrrroooouuuugggghhhh tttthhhheeee hhhheeeeaaaaddddssss ooooffff
tttthhhheeee ppppiiiinnnnssss ppppiiiieeeerrrrcccceeeedddd iiiinnnn ffffrrrroooonnnntttt ooooffff mmmmiiiirrrrrrrroooorrrr.... ((((AAAASSSS3333))))
1. Take a drawing board and fix a white paper on it with the help of clamps.
3. Join R, S and O as shown in the figure.
4. We will find the incident ray , the reflected ray and normal are lying in the same surface.
NNNNooootttteeee:::: -- DDDDrrrraaaawwww tttthhhheeee ssssaaaammmmeeee ddddiiiiaaaaggggrrrraaaammmm ooooffff qqqquuuueeeessssttttiiiioooonnnn nnnnuuuummmmbbbbeeeerrrr 11114444 .
18.... CCCCoooolllllllleeeecccctttt tttthhhheeee iiiinnnnffffoooorrrrmmmmaaaattttiiiioooonnnn aaaabbbboooouuuutttt tttthhhheeee hhhhiiiissssttttoooorrrryyyy ooooffff sssspppphhhheeeerrrriiiiccccaaaallll mmmmiiiirrrrrrrroooorrrrssss iiiinnnn hhhhuuuummmmaaaannnn cccciiiivvvviiiilllliiiizzzzaaaattttiiiioooonnnn.... DDDDiiiissssppppllllaaaayyyy iiiinnnn yyyyoooouuuurrrr
ccccllllaaaassssssss rrrroooooooommmm.... ((((AAAASSSS4444))))
1. One of the famous examples is from the Greek Archimedes, who burnt ships with parabolic
2. Metal coated glass mirror, is invented in Sidon in 1st century A.D. mirrors.
3. Bronze mirror was manufactured from around 200 B.C.
4. Mirrors made from mixtures are also been produced in China and India.
19.... TTTThhhhiiiinnnnkkkk aaaabbbboooouuuutttt tttthhhheeee oooobbbbjjjjeeeecccctttt wwwwhhhhiiiicccchhhh aaaaccccttttssss aaaassss aaaa ccccoooonnnnccccaaaavvvveeee oooorrrr ccccoooonnnnvvvveeeexxxx mmmmiiiirrrrrrrroooorrrr iiiinnnn yyyyoooouuuurrrr ssssuuuurrrrrrrroooouuuunnnnddddiiiinnnnggggssss.... MMMMaaaakkkkeeee aaaa ttttaaaabbbblllleeee
aaaannnndddd ddddiiiissssppppllllaaaayyyy iiiinnnn yyyyoooouuuurrrr ccccllllaaaassssssss rrrroooooooommmm ((((AAAASSSS4444))))
CCCCoooonnnnccccaaaavvvveeee CCCCoooonnnnvvvveeeexxxx
1. Spoon bulged inwards. 1. Spoon bulged outwards.
2. Inner surface of a steel basin. 2. Outer surface of a steel basin.
3. Inner surface of a cooking vessel. 3. Outer surface of a cooking vessel.
22220000.... HHHHoooowwww wwwwiiiillllllll oooouuuurrrr iiiimmmmaaaaggggeeee iiiinnnn ccccoooonnnnccccaaaavvvveeee aaaannnndddd ccccoooonnnnvvvveeeexxxx mmmmiiiirrrrrrrroooorrrrssss???? CCCCoooolllllllleeeecccctttt pppphhhhoooottttooooggggrrrraaaapppphhhhssss aaaannnndddd ddddiiiissssppppllllaaaayyyy iiiinnnn yyyyoooouuuurrrr ccccllllaaaassssssss
rrrroooooooommmm.... ((((AAAASSSS4444))))
1. In concave mirror our image is thin.
2. In convex mirror our image is bulged out.

9
22221111.... DDDDrrrraaaawwww aaaannnndddd eeeexxxxppppllllaaaaiiiinnnn tttthhhheeee pppprrrroooocccceeeessssssss ooooffff ffffoooorrrrmmmmaaaattttiiiioooonnnn ooooffff iiiimmmmaaaaggggeeee wwwwiiiitttthhhh aaaa ppppiiiinnnnhhhhoooolllleeee ccccaaaammmmeeeerrrraaaa???? ((((AAAASSSS5555))))
FFFFoooorrrrmmmmaaaattttiiiioooonnnn ooooffff iiiimmmmaaaaggggeeee iiiinnnn ppppiiiinnnnhhhhoooolllleeee ccccaaaammmmeeeerrrraaaa:::: - 1. The light rays coming from the top of the candle flame
fall at different points on the screen.
2. Similarly the rays coming from bottom of the candle flame also fall at different points on the
3. Thus we get blurred image on the screen. screen.
22.... DDDDrrrraaaawwww ssssuuuuiiiittttaaaabbbblllleeee rrrraaaayyyyssss bbbbyyyy wwwwhhhhiiiicccchhhh wwwweeee ccccaaaannnn gggguuuueeeessssssss tttthhhheeee ppppoooossssiiiittttiiiioooonnnn ooooffff tttthhhheeee iiiimmmmaaaaggggeeee ffffoooorrrrmmmmeeeedddd bbbbyyyy aaaa ccccoooonnnnccccaaaavvvveeee mmmmiiiirrrrrrrroooorrrr.... ((((AAAASSSS5555))))
22223333.... SSSShhhhoooowwww tttthhhheeee ffffoooorrrrmmmmaaaattttiiiioooonnnn ooooffff iiiimmmmaaaaggggeeee wwwwiiiitttthhhh aaaa rrrraaaayyyy ddddiiiiaaaaggggrrrraaaammmm,,,, wwwwhhhheeeennnn aaaannnn oooobbbbjjjjeeeecccctttt iiiissss ppppllllaaaacccceeeedddd oooonnnn tttthhhheeee pppprrrriiiinnnncccciiiippppaaaallll aaaaxxxxiiiissss
ooooffff aaaa ccccoooonnnnccccaaaavvvveeee mmmmiiiirrrrrrrroooorrrr aaaawwwwaaaayyyy ffffrrrroooommmm tttthhhheeee cccceeeennnnttttrrrreeee ooooffff ccccuuuurrrrvvvvaaaattttuuuurrrreeee.... ((((AAAASSSS5555))))
22224444.... MMMMaaaakkkkeeee aaaa ssssoooollllaaaarrrr hhhheeeeaaaatttteeeerrrr////ccccooooooookkkkeeeerrrr aaaannnndddd eeeexxxxppppllllaaaaiiiinnnn tttthhhheeee pppprrrroooocccceeeessssssss ooooffff mmmmaaaakkkkiiiinnnngggg.... ((((AAAASSSS5555))))
1. Make a wooden/ iron frame in in the shape of TV dish.
2. Cut the acrylic mirror sheets in to 8 or 12 pieces in the
shape of isosceles triangles.
3. Stick the triangle mirrors to the dish as shown in the
figure.
4. Your solar heater/cooker is ready.

10
25. To form the image on the object itself, 222555... TTTooo fffooorrrmmm ttthhheee iiimmmaaagggeee ooonnn ttthhheee ooobbbjjjeeecccttt iiitttssseeelllfff,,, hhhhoooowwww sssshhhhoooouuuulllldddd wwwweeee ppppllllaaaacccceeee tttthhhheeee oooobbbbjjjjeeeecccctttt iiiinnnn ffffrrrroooonnnntttt ooooffff aaaa ccccoooonnnnccccaaaavvvveeee mmmmiiiirrrrrrrroooorrrr????
EEEExxxxppppllllaaaaiiiinnnn wwwwiiiitttthhhh aaaa rrrraaaayyyy ddddiiiiaaaaggggrrrraaaammmm.... ((((AAAASSSS5555))))
1. The object is placed on the centre of curvature of concave
mirror.
2. The reflected rays are converse at centre of curvature
only.
3. So, a real and inverted image with size equal to the size of
the object.
26.... HHHHoooowwww ddddoooo yyyyoooouuuu aaaapppppppprrrreeeecccciiiiaaaatttteeee tttthhhheeee rrrroooolllleeee ooooffff sssspppphhhheeeerrrriiiiccccaaaallll mmmmiiiirrrrrrrroooorrrrssss iiiinnnn oooouuuurrrr ddddaaaaiiiillllyyyy lllliiiiffffeeee???? ((((AAAASSSS6666))))
1. Spherical mirrors are used as rare-view mirror in the vehicles.
2. Dentists are also used the spherical mirrors.
3. Spherical mirrors are used in many large telescopes to observe the universe.
4. So, I appreciate spherical mirrors in our daily life.
22227777.... HHHHoooowwww ddddoooo yyyyoooouuuu aaaapppppppprrrreeeecccciiiiaaaatttteeee tttthhhheeee uuuusssseeee ooooffff rrrreeeefffflllleeeeccccttttiiiioooonnnn ooooffff lllliiiigggghhhhtttt bbbbyyyy aaaa ccccoooonnnnccccaaaavvvveeee mmmmiiiirrrrrrrroooorrrr iiiinnnn mmmmaaaakkkkiiiinnnngggg ooooffff TTTTVVVV aaaannnntttteeeennnnnnnnaaaa
ddddiiiisssshhhheeeessss???? ((((AAAASSSS6666))))
1. A concave mirror can converge the reflected rays to its focal points.
2. Because by this property of a concave mirror, the shape of TV dish antenna is designed.
3. Hence, I really appreciate the use of reflection of light by a concave mirror in making of TV
antenna dishes.
22228888.... HHHHaaaavvvveeee yyyyoooouuuu eeeevvvveeeerrrr oooobbbbsssseeeerrrrvvvveeeedddd tttthhhheeee iiiimmmmaaaaggggeeeessss ooooffff tttthhhheeee sssskkkkyyyy iiiinnnn rrrraaaaiiiinnnn wwwwaaaatttteeeerrrr ppppoooooooollllssss oooonnnn eeeeaaaarrrrtttthhhh???? EEEExxxxppppllllaaaaiiiinnnn tttthhhheeee rrrreeeefffflllleeeeccccttttiiiioooonnnn ooooffff
lllliiiigggghhhhtttt iiiinnnn tttthhhhiiiissss ccccoooonnnntttteeeexxxxtttt???? ((((AAAASSSS6666))))
1. The surface of rain water in pools act as a plane mirror.
2. So we can observe the virtual image of sky due to reflection of light from surface of rain pool.
22229999.... DDDDiiiissssccccuuuussssssss tttthhhheeee mmmmeeeerrrriiiittttssss aaaannnndddd ddddeeeemmmmeeeerrrriiiittttssss ooooffff uuuussssiiiinnnngggg mmmmiiiirrrrrrrroooorrrrssss iiiinnnn bbbbuuuuiiiillllddddiiiinnnngggg eeeelllleeeevvvvaaaattttiiiinnnngggg???? ((((AAAASSSS7777))))
MMMMeeeerrrriiiittttssss:::: - 1. They absorb heat energy.
2. They make the building attractive.
3. They are used to cool inside the building.
DDDDeeeemmmmeeeerrrriiiittttssss:::: - 1. Some mirrors used in buildings are easily breakable.
2. Birds confused because of the reflection of mirrors in building elevation.
3. It causes disturbance at night time because reflection confuses the vehicles.
30.... WWWWhhhhyyyy ddddoooo wwwweeee pppprrrreeeeffffeeeerrrr aaaa ccccoooonnnnvvvveeeexxxx mmmmiiiirrrrrrrroooorrrr aaaassss aaaa rrrreeeeaaaarrrr--vvvviiiieeeewwww mmmmiiiirrrrrrrroooorrrr iiiinnnn tttthhhheeee vvvveeeehhhhiiiicccclllleeeessss???? ((((AAAASSSS7777))))
1. Convex mirror always produce an erect and virtual image of the behind vehicle in the small
2. So, we prefer a convex mirror as a rear-view mirror in the vehicles. mirror.
,

- к
!
TTTTiiiimmmmeeee aaaa ddddiiiiccccttttaaaattttoooorrrr iiiittttssss ppppaaaatttthhhh rrrruuuulllleeeessss OOOOuuuurrrr ffffaaaatttteeee lllliiiinnnneeee-- UUUUnnnnddddeeeesssseeeerrrrvvvveeeedddd hhhhooooppppeeee aaaa sssshhhheeeeeeeerrrr wwwwaaaasssstttteeeellllaaaannnndddd iiiinnnnddddeeeeeeeedddd....

11
Chapter 5
Refraction at Plane Surface
1. Why 111... WWWhhhyyy iiiissss iiiitttt ddddiiiiffffffffiiiiccccuuuulllltttt ttttoooo sssshhhhooooooootttt aaaa ffffiiiisssshhhh sssswwwwiiiimmmmmmmmiiiinnnngggg iiiinnnn wwwwaaaatttteeeerrrr???? ((((AAAASSSS1111))))
1. It is very difficult to shoot a fish swimming in water.
2. Because its position appears to be shifted up from its original position due to reflection.
2222.... TTTThhhheeee ssssppppeeeeeeeedddd ooooffff tttthhhheeee lllliiiigggghhhhtttt iiiinnnn aaaa ddddiiiiaaaammmmoooonnnndddd iiiissss 1111,,,, 22224444,,,, 000000000000 kkkkmmmm////ssss.... FFFFiiiinnnndddd tttthhhheeee rrrreeeeffffrrrraaaaccccttttiiiivvvveeee iiiinnnnddddeeeexxxx ooooffff ddddiiiiaaaammmmoooonnnndddd iiiiffff tttthhhheeee ssssppppeeeeeeeedddd
of lllliiiigggghhhhtttt iiiinnnn aaaaiiiirrrr iiiissss 3333,,,, 00000000,,,,000000000000 kkkkmmmm////ssss.... ((((AAAASSSS1111)))) ((((AAAAnnnnssss:::: 2222....44442222))))
GGGGiiiivvvveeeennnn: - Speed of light in a Diamond = 1, 24, 000 km/s
Speed of light in air = 3, 00,000 km/s.
Refractive index of a Diamond =

=
,,
,, = 2.419= 2.42

.. WWWWhhhhaaaatttt iiiissss tttthhhheeee rrrreeeeffffrrrraaaaccccttttiiiivvvveeee iiiinnnnddddeeeexxxx ooooffff wwwwaaaatttteeeerrrr rrrreeeellllaaaattttiiiivvvveeee
3333.... RRRReeeeffffrrrraaaaccccttttiiiivvvveeee iiiinnnnddddeeeexxxx ooooffff ggggllllaaaassssssss rrrreeeellllaaaattttiiiivvvveeee ttttoooo wwwwaaaatttteeeerrrr iiiissss
ttttoooo ggggllllaaaassssssss???? ((((AAAASSSS1111)))) ((((AAAAnnnnssss::::

)
GGGGiiiivvvveeeennnn :- Refractive index of glass relative to water is =

=

Refractive index of water relative to glass =

=

4444.... TTTThhhheeee aaaabbbbssssoooolllluuuutttteeee rrrreeeeffffrrrraaaaccccttttiiiivvvveeee iiiinnnnddddeeeexxxx ooooffff wwwwaaaatttteeeerrrr iiiissss

.. WWWWhhhhaaaatttt iiiissss tttthhhheeee ccccrrrriiiittttiiiiccccaaaallll aaaannnngggglllleeee ooooffff iiiitttt???? ((((AAAASSSS1111)))) ((((AAAAnnnnssss:::: 884....55550)
GGGGiiiivvvveeeennnn :- The absolute refractive index of water =

! =

→ Sin C =

→ Sin C = 0.75 → Sin C = sin 84.5o → C= 84.50
5555.... DDDDeeeetttteeeerrrrmmmmiiiinnnneeee tttthhhheeee rrrreeeeffffrrrraaaaccccttttiiiivvvveeee iiiinnnnddddeeeexxxx ooooffff bbbbeeeennnnzzzzeeeennnneeee iiiiffff tttthhhheeee ccccrrrriiiittttiiiiccccaaaallll aaaannnngggglllleeee ooooffff iiiitttt iiiissss 444422220....((((AAAASSSS1111)))) ((((AAAAnnnnssss:::: 1111....55551111))))
GGGGiiiivvvveeeennnn :- The critical angle of Benzene = 420
Refractive index of Benzene =

$ =

=

. =

=1.51
6.... EEEExxxxppppllllaaaaiiiinnnn tttthhhheeee ffffoooorrrrmmmmaaaattttiiiioooonnnn ooooffff mmmmiiiirrrraaaaggggeeee ????((((AAAASSSS1111))))
MMMMiiiirrrraaaaggggeeee :- Mirage is an optical illusion where it appears that water is collected on the road at a
distant place but when we get there, we don’t find any water.
FFFFoooorrrrmmmmaaaattttiiiioooonnnn :- 1. During the hot summer day, air just above the road surface is very hot and the air
at higher altitudes is cool.
2. Light travels faster through the thinner hot air than through, the denser cool air above it.
3. When light falls from tall object such as tree or from the sky passes through a medium just above
the road.
4. Due to the refraction of light ,we fell the illusion of water being present on road.
5. This is called a mirage.

12
7. How do you verify 777... HHHooowww dddooo yyyooouuu vvveeerrriiifffyyy eeeexxxxppppeeeerrrriiiimmmmeeeennnnttttaaaallllllllyyyy tttthhhhaaaatttt
'() (
'() * iiiissss ccccoooonnnnssssttttaaaannnntttt ???? ((((AAAASSSS1111))))
AAAAiiiimmmm: - To verify that

is a constant.
MMMMaaaatttteeeerrrriiiiaaaallllssss rrrreeeeqqqquuuuiiiirrrreeeedddd:- A plank, white chart, protractor, scale, small
black painted plank, a semi circular glass disc of thickness nearly
2cm pencil and laser light.
PPPPrrrroooocccceeeedddduuuurrrreeee :- 1. Make a chart as shown in the figure.
2. Place a semi-circle glass disc so that its diameter coincides with the line “MM”
3. Send a laser light along a line which makes 150 with “NN”.
4. Measure its corresponding angle of refraction by observing light coming from outside of
the glass slab.
5. Repeat this experiment with various values of angle of incidence, refraction and noted
below.
S.No i r Sin i Sin r +,- ,
6. From the above table we observe that
+,- .

is a constant.
8888.... EEEExxxxppppllllaaaaiiiinnnn tttthhhheeee pppphhhheeeennnnoooommmmeeeennnnoooonnnn ooooffff ttttoooottttaaaallll iiiinnnntttteeeerrrrnnnnaaaallll rrrreeeefffflllleeeeccccttttiiiioooonnnn wwwwiiiitttthhhh oooonnnneeee oooorrrr ttttwwwwoooo aaaaccccttttiiiivvvviiiittttiiiieeeessss????((((AAAASSSS1111))))
1. Take a cylindrical transparent vessel and place a coin at the bottom of the vessel.
2. Now pour water until you get the image of the coin on the water surface.
3. Formation of the image of the coin is due to total internal reflection.
9999.... HHHHoooowwww ddddoooo yyyyoooouuuu vvvveeeerrrriiiiffffyyyy eeeexxxxppppeeeerrrriiiimmmmeeeennnnttttaaaallllllllyyyy tttthhhhaaaatttt tttthhhheeee aaaannnngggglllleeee oooo rrrreeeeffffrrrraaaaccccttttiiiioooonnnn iiiissss mmmmoooorrrreeee tttthhhhaaaannnn aaaannnngggglllleeee ooooffff iiiinnnncccciiiiddddeeeennnncccceeee wwwwhhhheeeennnn
lllliiiigggghhhhtttt rrrraaaayyyyssss ttttrrrraaaavvvveeeellll ffffrrrroooommmm ddddeeeennnnsssseeeerrrr ttttoooo rrrraaaarrrreeeerrrr mmmmeeeeddddiiiiuuuummmm ???? ((((AAAASSSS1111))))
1. Consider that a light travels from medium-1 with speed V1 to
medium-2 with speed V2 as shown in the figure.
2. Here V2 V1 means medium-1 is denser medium and medium-2 is
rarer medium.
3. When light travels from denser medium to rarer medium the angle
of incident is less than the angle refraction.
4. This means angle o refraction is more than angle of incident when
light travels from denser medium to rarer medium.

13
11110000.... TTTTaaaakkkkeeee aaaa bbbbrrrriiiigggghhhhtttt mmmmeeeettttaaaallll bbbbaaaallllllll aaaannnndddd mmmmaaaakkkkeeee iiiitttt bbbbllllaaaacccckkkk wwwwiiiitttthhhh ssssooooooootttt iiiinnnn aaaa ccccaaaannnnddddlllleeee ffffllllaaaammmmeeee.... IIIImmmmmmmmeeeerrrrsssseeee iiiitttt iiiinnnn wwwwaaaatttteeeerrrr.... HHHHoooowwww
ddddooooeeeessss iiiitttt aaaappppppppeeeeaaaarrrr aaaannnndddd wwwwhhhhyyyy???? ((((MMMMaaaakkkkeeee hhhhyyyyppppooootttthhhheeeessssiiiissss aaaannnndddd ddddoooo tttthhhheeee aaaabbbboooovvvveeee eeeexxxxppppeeeerrrriiiimmmmeeeennnntttt)))).... ((((AAAASSSS2222))))
1. The metallic ball appeared to be raised up in the water.
2. The path of the ray changes its direction at the interface, separating the two media i.e air and
water.
11111111.... TTTTaaaakkkkeeee aaaa ggggllllaaaassssssss vvvveeeesssssssseeeellll aaaannnndddd ppppoooouuuurrrr ssssoooommmmeeee ggggllllyyyycccceeeerrrriiiinnnn iiiinnnnttttoooo vvvveeeesssssssseeeellll aaaannnndddd nnnneeeexxxxtttt ppppoooouuuurrrr wwwwaaaatttteeeerrrr uuuupppp ttttoooo tttthhhheeee bbbbrrrriiiimmmm....
TTTTaaaakkkkeeee aaaa qqqquuuuaaaarrrrttttzzzz ggggllllaaaassssssss rrrroooodddd.... KKKKeeeeeeeepppp iiiitttt iiiinnnn tttthhhheeee vvvveeeesssssssseeeellll.... OOOObbbbsssseeeerrrrvvvveeee ggggllllaaaassssssss rrrroooodddd bbbbyyyy tttthhhheeee ssssiiiiddddeeeessss ooooffff ggggllllaaaassssssss vvvveeeesssssssseeeellll....
*WWWWhhhhaaaatttt cccchhhhaaaannnnggggeeeessss ddddoooo yyyyoooouuuu nnnnoooottttiiiicccceeee???? * WWWWhhhhaaaatttt ccccoooouuuulllldddd bbbbeeee tttthhhheeee rrrreeeeaaaassssoooonnnnssss ffffoooorrrr tttthhhheeeesssseeee cccchhhhaaaannnnggggeeeessss???? ((((AAAASSSS2222))))
1. We cannot see the glass rod in glycerin, but we can see the rod in water.
2. We also observe a clear image of glass rod in water.
RRRReeeeaaaassssoooonnnn: - Glycerin and glass have same refractive index. So we are unable to see the glass rod in
glycerin.
11112222.... DDDDoooo aaaaccccttttiiiivvvviiiittttyyyy--7777 aaaaggggaaaaiiiinnnn.... HHHHoooowwww ccccaaaannnn yyyyoooouuuu ffffiiiinnnndddd ccccrrrriiiittttiiiiccccaaaallll aaaannnngggglllleeee ooooffff wwwwaaaatttteeeerrrr???? EEEExxxxppppllllaaaaiiiinnnn yyyyoooouuuurrrr sssstttteeeeppppssss bbbbrrrriiiieeeeffffllllyyyy.... ((((AAAASSSS3333))))
1. You might have observed a coin kept at the bottom of a vessel filled with water appears to be
raised.
2. The refractive index of water is 1.33
3. So critical angle of water, Sin C =

/0

1
2 (
) =

.
Sin C = 0.7518
Sin C = Sin 48.70 → C = 48.70
4. The critical angle of water = 48.7o
11113333.... CCCCoooolllllllleeeecccctttt tttthhhheeee vvvvaaaalllluuuueeeessss ooooffff rrrreeeeffffrrrraaaaccccttttiiiivvvveeee iiiinnnnddddeeeexxxx ooooffff tttthhhheeee ffffoooolllllllloooowwwwiiiinnnngggg mmmmeeeeddddiiiiaaaa.... ((((AAAASSSS4444))))
WWWWaaaatttteeeerrrr,,,, ccccooooccccoooonnnnuuuutttt ooooiiiillll,,,, fffflllliiiinnnntttt ggggllllaaaassssssss,,,, ccccrrrroooowwwwnnnn ggggllllaaaassssssss,,,, ddddiiiiaaaammmmoooonnnndddd,,,, bbbbeeeennnnzzzzeeeennnneeee aaaannnndddd hhhhyyyyddddrrrrooooggggeeeennnn ggggaaaassss....
SSSS....NNNNoooo MMMMaaaatttteeeerrrriiiiaaaallll MMMMeeeeddddiiiiuuuummmm RRRReeeeffffrrrraaaaccccttttiiiivvvveeee iiiinnnnddddeeeexxxx
1 Water 1.33
2 Coconut oil 1.445
3 Flint glass 1.65
4 Crown glass 1.52
5 Diamond 2.42
6 Benzene 1.50
7 Hydrigen ------

14
14. Collect information on ... CCCooolllllleeecccttt iiinnnfffooorrrmmmaaatttiiiooonnn ooonnn wwwwoooorrrrkkkkiiiinnnngggg ooooffff ooooppppttttiiiiccccaaaallll ffffiiiibbbbeeeerrrrssss.... PPPPrrrreeeeppppaaaarrrreeee aaaa rrrreeeeppppoooorrrrtttt aaaabbbboooouuuutttt vvvvaaaarrrriiiioooouuuussss uuuusssseeeessss ooooffff ooooppppttttiiiiccccaaaallll ffffiiiibbbbrrrreeeessss
iiiinnnn oooouuuurrrr ddddaaaaiiiillllyyyy lllliiiiffffeeee.... ((((AAAASSSS4444))))
OOOOppppttttiiiiccccaaaallll ffffiiiibbbbeeeerrrrssss: - 1. Fibers works on the principle of total internal reflection.
2. Fiber is made up of plastic or glass and its diameter is one micro meter (10-6 m).
3. Optical fibers are used to test the intestines of a human body.
4. Fiber optics are used to transmit the communication signals through light pipes.
15.... TTTTaaaakkkkeeee aaaa tttthhhhiiiinnnn tttthhhheeeerrrrmmmmooooccccoooollll sssshhhheeeeeeeetttt.... CCCCuuuutttt iiiitttt iiiinnnn cccciiiirrrrccccuuuullllaaaarrrr ddddiiiissssccccssss ooooffff ddddiiiiffffffffeeeerrrreeeennnntttt rrrraaaaddddiiiiiiii lllliiiikkkkeeee 2222ccccmmmm,,,, 3333ccccmmmm,,,, 4444ccccmmmm,,,, 4444....5555ccccmmmm,,,, 5555ccccmmmm
eeeettttcccc aaaannnndddd mmmmaaaarrrrkkkk cccceeeennnntttteeeerrrrssss wwwwiiiitttthhhh sssskkkkeeeettttcccchhhh ppppeeeennnn.... NNNNoooowwww ttttaaaakkkkeeee nnnneeeeeeeeddddlllleeeessss ooooffff lllleeeennnnggggtttthhhh nnnneeeeaaaarrrrllllyyyy 6ccccmmmm.... PPPPiiiinnnn aaaa nnnneeeeeeeeddddlllleeee ttttoooo eeeeaaaacccchhhh ddddiiiisssscccc
aaaatttt iiiittttssss cccceeeennnnttttrrrreeee vvvveeeerrrrttttiiiiccccaaaallllllllyyyy.... TTTTaaaakkkkeeee wwwwaaaatttteeeerrrr iiiinnnn aaaa llllaaaarrrrggggeeee ooooppppaaaaqqqquuuueeee ttttrrrraaaayyyy aaaannnndddd ppppllllaaaacccceeee tttthhhheeee ddddiiiisssscccc wwwwiiiitttthhhh 2222ccccmmmm rrrraaaaddddiiiiuuuussss iiiinnnn ssssuuuucccchhhh aaaa wwwwaaaayyyy
tttthhhhaaaatttt tttthhhheeee nnnneeeeeeeeddddlllleeee mmmmuuuusssstttt bbbbeeee iiiinnnnssssiiiiddddeeee tttthhhheeee wwwwaaaatttteeeerrrr aaaassss sssshhhhoooowwwwnnnn iiiinnnn ffffiiiigggguuuurrrreeee.... NNNNoooowwww ttttrrrryyyy ttttoooo vvvviiiieeeewwww tttthhhheeee ffffrrrreeeeeeee eeeennnndddd ((((hhhheeeeaaaadddd)))) ooooffff tttthhhheeee
nnnneeeeeeeeddddlllleeee ffffrrrroooommmm ssssuuuurrrrffffaaaacccceeee ooooffff tttthhhheeee wwwwaaaatttteeeerrrr....
aaaa)))).... DDDDiiiidddd yyyyoooouuuu aaaabbbblllleeee ttttoooo sssseeeeeeee tttthhhheeee hhhheeeeaaaadddd ooooffff tttthhhheeee nnnneeeeeeeeddddlllleeee????
NNNNoooowwww ddddoooo tttthhhheeee ssssaaaammmmeeee wwwwiiiitttthhhh ooootttthhhheeeerrrr ddddiiiissssccccssss ooooffff ddddiiiiffffffffeeeerrrreeeennnntttt rrrraaaaddddiiiiiiii.... TTTTrrrryyyy ttttoooo sssseeeeeeee tttthhhheeee hhhheeeeaaaadddd ooooffff
tttthhhheeee nnnneeeeeeeeddddlllleeee,,,, eeeeaaaacccchhhh ttttiiiimmmmeeee....
NNNNooootttteeee:::: tttthhhheeee ppppoooossssiiiittttiiiioooonnnn ooooffff yyyyoooouuuurrrr eeeeyyyyeeee aaaannnndddd tttthhhheeee ppppoooossssiiiittttiiiioooonnnn ooooffff tttthhhheeee ddddiiiisssscccc oooonnnn wwwwaaaatttteeeerrrr ssssuuuurrrrffffaaaacccceeee sssshhhhoooouuuulllldddd nnnnooootttt bbbbeeee
cccchhhhaaaannnnggggeeeedddd wwwwhhhhiiiilllleeee rrrreeeeppppeeeeaaaattttiiiinnnngggg tttthhhheeee aaaaccccttttiiiivvvviiiittttyyyy wwwwiiiitttthhhh ooootttthhhheeeerrrr ddddiiiissssccccssss....
bbbb)))).... AAAAtttt wwwwhhhhaaaatttt mmmmaaaaxxxxiiiimmmmuuuummmm rrrraaaaddddiiiiuuuussss ooooffff ddddiiiisssscccc,,,, ddddiiiidddd yyyyoooouuuu nnnnooootttt aaaabbbblllleeee ttttoooo sssseeeeeeee tttthhhheeee ffffrrrreeeeeeee eeeennnndddd ooooffff tttthhhheeee nnnneeeeeeeeddddlllleeee????
cccc)))).... WWWWhhhhyyyy ddddiiiiddddnnnn’’’’tttt yyyyoooouuuu aaaabbbblllleeee ttttoooo vvvviiiieeeewwww tttthhhheeee hhhheeeeaaaadddd ooooffff tttthhhheeee nnnnaaaaiiiillll ffffoooorrrr cccceeeerrrrttttaaaaiiiinnnn rrrraaaaddddiiiiiiii ooooffff tttthhhheeee ddddiiiissssccccssss????
dddd)))).... DDDDooooeeeessss tttthhhhiiiissss aaaaccccttttiiiivvvviiiittttyyyy hhhheeeellllpppp yyyyoooouuuu ttttoooo ffffiiiinnnndddd tttthhhheeee ccccrrrriiiittttiiiiccccaaaallll aaaannnngggglllleeee ooooffff tttthhhheeee mmmmeeeeddddiiiiuuuummmm ((((wwwwaaaatttteeeerrrr))))????
eeee)))).... DDDDrrrraaaawwww aaaa ddddiiiiaaaaggggrrrraaaammmm ttttoooo sssshhhhoooowwww tttthhhheeee ppppaaaassssssssaaaaggggeeee ooooffff lllliiiigggghhhhtttt rrrraaaayyyy ffffrrrroooommmm tttthhhheeee hhhheeeeaaaadddd ooooffff tttthhhheeee nnnnaaaaiiiillll iiiinnnn ddddiiiiffffffffeeeerrrreeeennnntttt ssssiiiittttuuuuaaaattttiiiioooonnnnssss.... ((((AAAASSSS4444))))
1. Yes, we can see the head of the needle.
2. At radius of 6 cm, we cannot see the free end of the needle.
3. Because the light ray coming from the object undergoing total internal reflection by touching the
surface of disc.
4. Yes, this activity helps us to find the critical angle of the medium (water).
Sin C =
/0

(
) =
.
. = 0.7521
Sin C = Sin 48.70
Critical angle, C = 48.70
5.

15
16. Explain the refraction of light through the glass ... EEExxxppplllaaaiiinnn ttthhheee rrreeefffrrraaaccctttiiiooonnn ooofff llliiiggghhhttt ttthhhrrrooouuuggghhh ttthhheee ggglllaaassssss ssssllllaaaabbbb wwwwiiiitttthhhh aaaa nnnneeeeaaaatttt rrrraaaayyyy ddddiiiiaaaaggggrrrraaaammmm.... ((((AAAASSSS5555))))
1. Place a piece of chart on a plank and Clamp it.
2. Place a glass slab in the middle of the paper. Draw border line along the edges of the slab by
using a pencil.
3. Name the vertices of the rectangle as A, B, C and D.
4. Make the arrangement as shown in the figure.
5. The refraction of light through the glass slab is as shown in the figure.
6. From the figure we noticed that the incident ray and emergent ray are parallel.
17.... PPPPllllaaaacccceeee aaaannnn oooobbbbjjjjeeeecccctttt oooonnnn tttthhhheeee ttttaaaabbbblllleeee.... LLLLooooooookkkk aaaatttt tttthhhheeee oooobbbbjjjjeeeecccctttt tttthhhhrrrroooouuuugggghhhh tttthhhheeee ttttrrrraaaannnnssssppppaaaarrrreeeennnntttt ggggllllaaaassssssss ssssllllaaaabbbb.... YYYYoooouuuu wwwwiiiillllllll oooobbbbsssseeeerrrrvvvveeee tttthhhhaaaatttt
iiiitttt wwwwiiiillllllll aaaappppppppeeeeaaaarrrr cccclllloooosssseeeerrrr ttttoooo yyyyoooouuuu.... DDDDrrrraaaawwww aaaa rrrraaaayyyy ddddiiiiaaaaggggrrrraaaammmm ttttoooo sssshhhhoooowwww ppppaaaassssssssaaaaggggeeee ooooffff lllliiiigggghhhhtttt rrrraaaayyyy iiiinnnn tttthhhhiiiissss ssssiiiittttuuuuaaaattttiiiioooonnnn.... ((((AAAASSSS5555))))
18.... WWWWhhhhaaaatttt iiiissss tttthhhheeee rrrreeeeaaaassssoooonnnn bbbbeeeehhhhiiiinnnndddd tttthhhheeee sssshhhhiiiinnnniiiinnnngggg ooooffff ddddiiiiaaaammmmoooonnnndddd aaaannnndddd hhhhoooowwww ddddoooo yyyyoooouuuu aaaapppppppprrrreeeecccciiiiaaaatttteeee iiiitttt???? ((((AAAASSSS6))))
1. Total internal reflection is the main reason behind the shining of diamond.
2. Diamond has high refractive index (2.41) and very low critical angle (24.40).
3. These are responsible for total internal reflection to take place in it.
4. So, I appreciate the diamond for shining.
19.... HHHHoooowwww ddddoooo yyyyoooouuuu aaaapppppppprrrreeeecccciiiiaaaatttteeee tttthhhheeee rrrroooolllleeee ooooffff FFFFeeeerrrrmmmmaaaatttt pppprrrriiiinnnncccciiiipppplllleeee iiiinnnn ddddrrrraaaawwwwiiiinnnngggg aaaa rrrraaaayyyy ddddiiiiaaaaggggrrrraaaammmm???? ((((AAAASSSS6))))
1. Fermat principle shows that light always takes the path of least amount of time.
2. This principle enables us to draw the ray diagram to explain the phenomena of light.
3. This principle also enables us to draw the ray diagram of reflection of light.
4. So, we appreciate the role of Fermat principle in drawing a ray diagram.

16
22220000.... AAAA lllliiiigggghhhhtttt rrrraaaayyyy iiiissss iiiinnnncccciiiiddddeeeennnntttt oooonnnn aaaaiiiirrrr-lllliiiiqqqquuuuiiiidddd iiiinnnntttteeeerrrrffffaaaacccceeee aaaatttt 444455550aaaannnndddd iiiissss rrrreeeeffffrrrraaaacccctttteeeedddd aaaatttt 333300000.... WWWWhhhhaaaatttt iiiissss tttthhhheeee rrrreeeeffffrrrraaaaccccttttiiiivvvveeee iiiinnnnddddeeeexxxx
ooooffff tttthhhheeee lllliiiiqqqquuuuiiiidddd???? FFFFoooorrrr wwwwhhhhaaaatttt aaaannnngggglllleeee ooooffff iiiinnnncccciiiiddddeeeennnncccceeee wwwwiiiillllllll tttthhhheeee aaaannnngggglllleeee bbbbeeeettttwwwweeeeeeeennnn rrrreeeefffflllleeeecccctttteeeedddd rrrraaaayyyy aaaannnndddd rrrreeeeffffrrrraaaacccctttteeeedddd rrrraaaayyyy bbbbeeee 999900000????
((((AAAASSSS7777)))) ((((AAAAnnnnssss:::: 1111....444411114444,,,, 55554444....77770)
GGGGiiiivvvveeeennnn:::: -- The angle of incidence, i = 450
The angle of refraction, r = 300
Refractive index of a liquid (n) =
!

=

5

=
6
√8
6
8
=

√ x

= √2 = 1.414
The refractive index of a liquid is 1.414
We know angle of refraction (r) =90- Angle of incident
Refractive index (n) =
!

→ 1.414 =
!

(: ) →

$ = 1.414 → tan i = 1.414
→ tan i = tan 54.70 → ˪i = 54.70
Critical angle = 54.70
22221111.... EEEExxxxppppllllaaaaiiiinnnn wwwwhhhhyyyy aaaa tttteeeesssstttt ttttuuuubbbbeeee iiiimmmmmmmmeeeerrrrsssseeeedddd aaaatttt aaaa cccceeeerrrrttttaaaaiiiinnnn aaaannnngggglllleeee iiiinnnn aaaa ttttuuuummmmbbbblllleeeerrrr ooooffff wwwwaaaatttteeeerrrr aaaappppppppeeeeaaaarrrrssss ttttoooo hhhhaaaavvvveeee aaaa mmmmiiiirrrrrrrroooorrrr
ssssuuuurrrrffffaaaacccceeee ffffoooorrrr aaaa cccceeeerrrrttttaaaaiiiinnnn vvvviiiieeeewwwwiiiinnnngggg ppppoooossssiiiittttiiiioooonnnn???? ((((AAAASSSS7777))))
1. When the glass tube is immersed in the water it appears to have a mirror surface.
2. Because they get total internally reflected.
3. So they appear to come from the surface of the tube itself.
22222222.... WWWWhhhhaaaatttt iiiissss tttthhhheeee aaaannnngggglllleeee ooooffff ddddeeeevvvviiiiaaaattttiiiioooonnnn pppprrrroooodddduuuucccceeeedddd bbbbyyyy tttthhhheeee ggggllllaaaassssssss ssssllllaaaabbbb???? EEEExxxxppppllllaaaaiiiinnnn wwwwiiiitttthhhh rrrraaaayyyy ddddiiiiaaaaggggrrrraaaammmm.... ((((AAAASSSS7777))))
1. Place a piece of chart on a plank and Clamp it.
2. Place a glass slab in the middle of the paper. Draw border line along the edges of the slab by
using a pencil.
3. Name the vertices of the rectangle as A, B, C and D.
4. Make the arrangement as shown in the figure.
5. The refraction of light through the glass slab is as shown in the figure.
6. From the figure we noticed that the incident ray and emergent ray are parallel.
22223333.... IIIInnnn wwwwhhhhaaaatttt ccccaaaasssseeeessss aaaa lllliiiigggghhhhtttt rrrraaaayyyy ddddooooeeeessss nnnnooootttt ddddeeeevvvviiiiaaaatttteeee aaaatttt iiiinnnntttteeeerrrrffffaaaacccceeee ooooffff ttttwwwwoooo mmmmeeeeddddiiiiaaaa???? ((((AAAASSSS7777))))
Alight ray does not deviate at interface of two media when it is incident normally at a point on the
interface of two media.

17
24. A ray of light travels from an optically denser to rarer medium. The critical ... AAA rrraaayyy ooofff llliiiggghhhttt tttrrraaavvveeelllsss fffrrrooommm aaannn oooppptttiiicccaaallllllyyy dddeeennnssseeerrr tttooo rrraaarrreeerrr mmmeeedddiiiuuummm... TTThhheee cccrrriiitttiiicccaaalll aaaannnngggglllleeee ooooffff tttthhhheeee ttttwwwwoooo
mmmmeeeeddddiiiiaaaa iiiissss ‘‘‘‘cccc’’’’.... WWWWhhhhaaaatttt iiiissss tttthhhheeee mmmmaaaaxxxxiiiimmmmuuuummmm ppppoooossssssssiiiibbbblllleeee ddddeeeevvvviiiiaaaattttiiiioooonnnn ooooffff tttthhhheeee rrrraaaayyyy???? ((((AAAASSSS7777)))) ((((AAAAnnnnssss::::P-2222cccc))))
GGGGiiiivvvveeeennnn: - The critical angle = C
The maximum angle of deviation of the ray = P -(C+C) = P -2C
25.... WWWWhhhheeeennnn wwwweeee ssssiiiitttt aaaatttt ccccaaaammmmpppp ffffiiiirrrreeee,,,, oooobbbbjjjjeeeeccccttttssss bbbbeeeeyyyyoooonnnndddd tttthhhheeee ffffiiiirrrreeee sssseeeeeeeennnn sssswwwwaaaayyyyiiiinnnngggg.... GGGGiiiivvvveeee tttthhhheeee rrrreeeeaaaassssoooonnnn ffffoooorrrr iiiitttt.... ((((AAAASSSS7777))))
1. When we sit at camp fire, objects beyond the fire seen swaying.
2. This happens due to refraction of light
3. The rays of light get reflected when thy passes through hot air to cold air.
4. So we observe the objects beyond the fire seen sawing.
26.... WWWWhhhhyyyy ddddoooo ssssttttaaaarrrrssss aaaappppppppeeeeaaaarrrr ttttwwwwiiiinnnnkkkklllliiiinnnngggg???? ((((AAAASSSS7777))))
Stars appear twinkling due to multiple refraction at different layers of air of different densities; the
light undergoes all the way to reach our eye.
27.... WWWWhhhhyyyy ddddooooeeeessss aaaa ddddiiiiaaaammmmoooonnnndddd sssshhhhiiiinnnneeee mmmmoooorrrreeee tttthhhhaaaannnn aaaa ggggllllaaaassssssss ppppiiiieeeecccceeee ccccuuuutttt ttttoooo tttthhhheeee ssssaaaammmmeeee sssshhhhaaaappppeeee???? ((((AAAASSSS7777))))
1. Diamond exhibits the property of total internal reflection due to its high refractive index and
low critical angle.
2. So, diamond shine more than a glass piece cut to the same shape.
BBBBOOOOOOOOKKKK BBBBIIIINNNNDDDDEEEERRRR BBBBEEEECCCCAAAAMMMMEEEE AAAANNNN EEEEXXXXPPPPEEEERRRRIIIIMMMMEEEENNNNTTTTAAAALLLL PPPPHHHHYYYYIIIICCCCIIIISSSSTTTT
MMMMiiiicccchhhhaaaaeeeellll FFFFaaaarrrraaaaddddaaaayyyy ((((1111777799991111–1111888867777))))
Michael Faraday was an experimental physicist. He had no
formal education. He came from a poor family. His father was a brick layer. He
learned the formal education in the lap his mother. He worked in a book-binding
shop during his early years. He used to read books that came for binding. This way
Faraday developed his interest in science. He got an opportunity to listen to some
public lectures by Humphrey Davy of Royal Institute. He made careful notes of Davy’s
lectures and sent them to Davy. Soon he was made an assistant in Davy’s laboratory at the Royal Institute.
Faraday made several path-breaking discoveries that include electromagnetic induction and the laws of
electrolysis. Several universities conferred on him the honorary degrees but he turned down such honours.
Faraday loved his science work more than any honour.

к к - к .
Chhhhiiiillllddddrrrreeeennnn fffflllloooocccckkkkiiiinnnngggg bbbbuuuutttttttteeeerrrrfffflllliiiieeeessss oooonnnn sssscccchhhhoooooooollll pppprrrreeeecccciiiinnnnccccttttssss – KKKKnnnnoooowwwwlllleeeeddddggggeeee, tttthhhheeeeiiiirrrr,, ffffiiiinnnneeeesssstttt nnnneeeeccccttttaaaarrrr....

18
Chapter CCChhhaaapppttteeerrr 6666
RRRReeeeffffrrrraaaaccccttttiiiioooonnnn aaaatttt CCCCuuuurrrrvvvveeeedddd SSSSuuuurrrrffffaaaacccceeee
1111.... AAAA mmmmaaaannnn wwwwaaaannnnttttssss ttttoooo ggggeeeetttt aaaa ppppiiiiccccttttuuuurrrreeee ooooffff aaaa zzzzeeeebbbbrrrraaaa.... HHHHeeee pppphhhhoooottttooooggggrrrraaaapppphhhheeeedddd aaaa wwwwhhhhiiiitttteeee ddddoooonnnnkkkkeeeeyyyy aaaafffftttteeeerrrr ffffiiiittttttttiiiinnnngggg aaaa ggggllllaaaassssssss,,,, wwwwiiiitttthhhh
bbbbllllaaaacccckkkk ssssttttrrrriiiippppeeeessss,,,, oooonnnn ttttoooo tttthhhheeee lllleeeennnnssss ooooffff hhhhiiiissss ccccaaaammmmeeeerrrraaaa.... WWWWhhhhaaaatttt pppphhhhoooottttoooo wwwwiiiillllllll hhhheeee ggggeeeetttt???? EEEExxxxppppllllaaaaiiiinnnn.... ((((AAAASSSS1111))))
1. He will get an image of white donkey because every part of lens forms an image.
2. So, if we cover the lens with strips still it forms a complete image.
3. However, the intensity of the image will be reduced.
2222.... TTTTwwwwoooo ccccoooonnnnvvvveeeerrrrggggiiiinnnngggg lllleeeennnnsssseeeessss aaaarrrreeee ttttoooo bbbbeeee ppppllllaaaacccceeeedddd iiiinnnn tttthhhheeee ppppaaaatttthhhh ooooffff ppppaaaarrrraaaalllllllleeeellll rrrraaaayyyyssss ssssoooo tttthhhhaaaatttt tttthhhheeee rrrraaaayyyyssss rrrreeeemmmmaaaaiiiinnnn ppppaaaarrrraaaalllllllleeeellll aaaafffftttteeeerrrr
ppppaaaassssssssiiiinnnngggg tttthhhhrrrroooouuuugggghhhh bbbbooootttthhhh lllleeeennnnsssseeeessss.... HHHHoooowwww sssshhhhoooouuuulllldddd tttthhhheeee lllleeeennnnsssseeeessss bbbbeeee aaaarrrrrrrraaaannnnggggeeeedddd???? EEEExxxxppppllllaaaaiiiinnnn wwwwiiiitttthhhh aaaa nnnneeeeaaaatttt rrrraaaayyyy ddddiiiiaaaaggggrrrraaaammmm.... ((((AAAASSSS1111))))
1. Arrange the two conversing lenses are to be placed in the path of parallel rays in such a way that
they should have common focal point between them.
2. The parallel rays of the first lens form a point source at the focal point.
3. Next the light rays travel in all directions and falls on the second lens and get refracted.
4. The refracted rays also travel parallel to each other and also to the principle axis.
5. Thus, forms a parallel beam of light rays.
3333.... TTTThhhheeee ffffooooccccaaaallll lllleeeennnnggggtttthhhh ooooffff aaaa ccccoooonnnnvvvveeeerrrrggggiiiinnnngggg lllleeeennnnssss iiiissss 22220000ccccmmmm.... AAAAnnnn oooobbbbjjjjeeeecccctttt iiiissss 66660000ccccmmmm ffffrrrroooommmm tttthhhheeee lllleeeennnnssss.... WWWWhhhheeeerrrreeee wwwwiiiillllllll tttthhhheeee iiiimmmmaaaaggggeeee bbbbeeee
ffffoooorrrrmmmmeeeedddd aaaannnndddd wwwwhhhhaaaatttt kkkkiiiinnnndddd ooooffff iiiimmmmaaaaggggeeee iiiissss iiiitttt???? ((((AAAASSSS1111))))
GGGGiiiivvvveeeennnn: - Focal length, f = 20 Cm
Object distance, u = - 60 Cm (In front of lens take as – ve sign)
Image distance, v =?

=

+

⟹

=

+

⟹

=

+

⟹

=

-

⟹

=

⟹

=

⟹ v =30 cm
∴ A real, diminished, inverted image formed at 30cm from the lens.

Linear Magnification, m =
=

=

=

Since m is negative, the image is real and inverted.

19
4. A double convex lens has two surfaces of equeal radii ‘R’ and refractive index n = 1.5. 444... AAA dddooouuubbbllleee cccooonnnvvveeexxx llleeennnsss hhhaaasss tttwwwooo sssuuurrrfffaaaccceeesss ooofff eeeqqquuueeeaaalll rrraaadddiiiiii ‘‘‘RRR’’’ aaannnddd rrreeefffrrraaaccctttiiivvveee iiinnndddeeexxx nnn === 111...555... FFFFiiiinnnndddd tttthhhheeee ffffooooccccaaaallll
lllleeeennnnggggtttthhhh ‘‘‘‘ffff’’’’.... ((((AAAASSSS1111))))
GGGGiiiivvvveeeennnn:- Refractive index = 1.5
Let R1 =R and R2 = -R
Lens makers formula is

= (n-1) [

-

]
= (1.5-1) (

-

)
= (1.5-1) (

+

)
= 0.5 (

)
= 0.5 x

=

∴ f = R
∴ The focal length is equeal to radiu of curvature.
5555.... WWWWrrrriiiitttteeee tttthhhheeee lllleeeennnnssss mmmmaaaakkkkeeeerrrrssss ffffoooorrrrmmmmuuuullllaaaa aaaannnndddd eeeexxxxppppllllaaaaiiiinnnn tttthhhheeee tttteeeerrrrmmmmssss iiiinnnn iiiitttt???? ((((AAAASSSS1111))))
Lens makers formula is

= (n-1) [

-

]
Here f = Focal length
R1 and R2 are radii of curvature.
n = Refractive index.
6666.... HHHHoooowwww ddddoooo yyyyoooouuuu vvvveeeerrrriiiiffffyyyy eeeexxxxppppeeeerrrriiiimmmmeeeennnnttttaaaallllllllyyyy tttthhhhaaaatttt tttthhhheeee ffffooooccccaaaallll lllleeeennnnggggtttthhhh ooooffff aaaa ccccoooonnnnvvvveeeexxxx lllleeeennnnssss iiiissss iiiinnnnccccrrrreeeeaaaasssseeeedddd wwwwhhhheeeennnn iiiitttt iiiissss kkkkeeeepppptttt iiiinnnn
waaaatttteeeerrrr???? ((((AAAASSSS1111))))
1. The arrangements are shown as shown in the figure.
2. Set the distance between stone and lens that is equeal
to less than the focal length of the lens.
3. We can see the image of the stone.
4. Now increase the distance between lens and stone
until we cannot view the image of the stone.
5. This shows that the focal length of lens has increased
in water.
7777.... HHHHoooowwww ddddoooo yyyyoooouuuu ffffiiiinnnndddd tttthhhheeee ffffooooccccaaaallll lllleeeennnnggggtttthhhh ooooffff tttthhhheeee lllleeeennnnssss eeeexxxxppppeeeerrrriiiimmmmeeeennnnttttaaaallllllllyyyy???? ((((AAAASSSS1111))))
1. Take the lens on v-type stand and keep it on a table such that it focuses towards the distant
object.
2. A white coated screen is placed on the other side of the lens and gets the clear image of the
object.
3. At this position measure the distance between the lens and the screen which is equeal to the focal
length of the lens.
i.e.

=

-

20
8888.... HHHHaaaarrrrsssshhhhaaaa tttteeeellllllllssss SSSSiiiiddddddddhhhhuuuu tttthhhhaaaatttt tttthhhheeee ddddoooouuuubbbblllleeee ccccoooonnnnvvvveeeexxxx lllleeeennnnssss bbbbeeeehhhhaaaavvvveeeessss lllliiiikkkkeeee aaaa ccccoooonnnnvvvveeeerrrrggggeeeennnntttt lllleeeennnnssss.... BBBBuuuutttt SSSSiiiiddddddddhhhhuuuu kkkknnnnoooowwwwssss tttthhhhaaaatttt
HHHHaaaarrrrsssshhhhaaaa’’’’ssss aaaasssssssseeeerrrrttttiiiioooonnnn iiiissss wwwwrrrroooonnnngggg aaaannnndddd ccccoooorrrrrrrreeeecccctttteeeedddd HHHHaaaarrrrsssshhhhaaaa bbbbyyyy aaaasssskkkkiiiinnnngggg ssssoooommmmeeee qqqquuuueeeessssttttiiiioooonnnnssss.... WWWWhhhhaaaatttt aaaarrrreeee tttthhhheeee qqqquuuueeeessssttttiiiioooonnnnssss
aaaasssskkkkeeeedddd bbbbyyyy SSSSiiiiddddddddhhhhuuuu???? ((((AAAASSSS2222))))
1. What is the convergent lens?
2. Is there a lens which is called as a convergent lens other than double convex lens?
3. Sindhu corrected Harsha’s assertion as: “A double convex lens is also known as convergent lens”
9999.... AAAAsssssssseeeerrrrttttiiiioooonnnn ((((AAAA)))):::: AAAA ppppeeeerrrrssssoooonnnn ssssttttaaaannnnddddiiiinnnngggg oooonnnn tttthhhheeee llllaaaannnndddd aaaappppppppeeeeaaaarrrrssss ttttaaaalllllllleeeerrrr tttthhhhaaaannnn hhhhiiiissss aaaaccccttttuuuuaaaallll hhhheeeeiiiigggghhhhtttt ttttoooo aaaa ffffiiiisssshhhh iiiinnnnssssiiiiddddeeee aaaa ppppoooonnnndddd....
((((AAAASSSS2222))))
RRRReeeeaaaassssoooonnnn ((((RRRR)):- LLLLiiiigggghhhhtttt bbbbeeeennnnddddssss aaaawwwwaaaayyyy ffffrrrroooommmm tttthhhheeee nnnnoooorrrrmmmmaaaallll aaaassss iiiitttt eeeennnntttteeeerrrrssss aaaaiiiirrrr ffffrrrroooommmm wwwwaaaatttteeeerrrr....
WWWWhhhhiiiicccchhhh ooooffff tttthhhheeee ffffoooolllllllloooowwwwiiiinnnngggg iiiissss ccccoooorrrrrrrreeeecccctttt???? EEEExxxxppppllllaaaaiiiinnnn....
aaaa)))) BBBBooootttthhhh AAAA aaaannnndddd RRRR aaaarrrreeee ttttrrrruuuueeee aaaannnndddd RRRR iiiissss tttthhhheeee ccccoooorrrrrrrreeeecccctttt eeeexxxxppppllllaaaannnnaaaattttiiiioooonnnn ooooffff AAAA....
bbbb)))) BBBBooootttthhhh AAAA aaaannnndddd RRRR aaaarrrreeee ttttrrrruuuueeee aaaannnndddd RRRR iiiissss nnnnooootttt tttthhhheeee ccccoooorrrrrrrreeeecccctttt eeeexxxxppppllllaaaannnnaaaattttiiiioooonnnn ooooffff AAAA....
cccc)))) AAAA iiiissss ttttrrrruuuueeee bbbbuuuutttt RRRR iiiissss ffffaaaallllsssseeee.... dddd)))) BBBBooootttthhhh AAAA aaaannnndddd RRRR aaaarrrreeee ffffaaaallllsssseeee....
eeee)))) AAAA iiiissss ffffaaaallllsssseeee bbbbuuuutttt RRRR iiiissss ttttrrrruuuueeee....
Both A and R are true and R is the correct explanation of A.
EEEExxxxppppllllaaaannnnaaaattttiiiioooonnnn: - 1. Let the actual height of the person be ‘x’ feet.
2.

=

3.

.
=

4. Apparent height of the man = 1.33X
= 1.33 times of the actual height of the person.
5. Hence the standing on the land appears taller than his actual height to a fish inside a pond.
11110000.... AAAA ccccoooonnnnvvvveeeexxxx lllleeeennnnssss iiiissss mmmmaaaaddddeeee uuuupppp ooooffff tttthhhhrrrreeeeeeee ddddiiiiffffffffeeeerrrreeeennnntttt mmmmaaaatttteeeerrrriiiiaaaallllssss aaaassss sssshhhhoooowwwwnnnn iiiinnnn tttthhhheeee ffffiiiigggguuuurrrreeee.... HHHHoooowwww mmmmaaaannnnyyyy ooooffff iiiimmmmaaaaggggeeeessss ddddooooeeeessss
iiiitttt ffffoooorrrrmmmmssss???? ((((AAAASSSS2222))))
1. A convex lens is made up of three different materials and its refractive indexes are •1 ,•2 and •3
respectively.
2. They form three different images for a same object at their three different foci as shown in the
figure.

21
11111111.... CCCCaaaannnn vvvviiiirrrrttttuuuuaaaallll iiiimmmmaaaaggggeeee bbbbeeee pppphhhhoooottttooooggggrrrraaaapppphhhheeeedddd bbbbyyyy aaaa ccccaaaammmmeeeerrrraaaa???? ((((AAAASSSS2222))))
Yes, a virtual image can be photographed by a camera.
12.... YYYYoooouuuu hhhhaaaavvvveeee aaaa lllleeeennnnssss.... SSSSuuuuggggggggeeeesssstttt aaaannnn eeeexxxxppppeeeerrrriiiimmmmeeeennnntttt ttttoooo ffffiiiinnnndddd oooouuuutttt tttthhhheeee ffffooooccccaaaallll lllleeeennnnggggtttthhhh ooooffff tttthhhheeee lllleeeennnnssss.... ((((AAAASSSS3333))))
1. Place the lens in a lens holder on the bench.
2. Position the wire gauge, object, a lamp and a plane mirror as shown in the figure.
3. Move the lens backwards or frontwards in relation to the object until you catch a clear image on
the screen.
4. Calculate the distance between the lens and object. It is equeal to focal length of the lens.
11113333.... LLLLeeeetttt uuuussss aaaassssssssuuuummmmeeee aaaa ssssyyyysssstttteeeemmmm tttthhhhaaaatttt ccccoooonnnnssssiiiissssttttssss ttttwwwwoooo lllleeeennnnsssseeeessss wwwwiiiitttthhhh ffffooooccccaaaallll lllleeeennnnggggtttthhhh ffff1 aaaannnndddd ffff2 rrrreeeessssppppeeeeccccttttiiiivvvveeeellllyyyy.... HHHHoooowwww ddddoooo yyyyoooouuuu
ffffiiiinnnndddd tttthhhheeee ffffooooccccaaaallll lllleeeennnnggggtttthhhh ooooffff tttthhhheeee ssssyyyysssstttteeeemmmm eeeexxxxppppeeeerrrriiiimmmmeeeennnnttttaaaallllllllyyyy,,,, wwwwhhhheeeennnn ((((AAAASSSS3333))))
iiii)))) TTTTwwwwoooo lllleeeennnnsssseeeessss aaaarrrreeee ttttoooouuuucccchhhhiiiinnnngggg eeeeaaaacccchhhh ooootttthhhheeeerrrr
iiiiiiii)))) TTTThhhheeeeyyyy aaaarrrreeee sssseeeeppppaaaarrrraaaatttteeeedddd bbbbyyyy aaaa ddddiiiissssttttaaaannnncccceeee‘‘‘‘dddd’’’’ wwwwiiiitttthhhh ccccoooommmmmmmmoooonnnn ooooppppttttiiiiccccaaaallll aaaaxxxxiiiissss....
iiii)))) FFFFooooccccaaaallll lllleeeennnnssss ooooffff ccccoooommmmbbbbiiiinnnnaaaattttiiiioooonnnn ooooffff ttttwwwwoooo lllleeeennnnsssseeeessss aaaarrrreeee ttttoooouuuucccchhhhiiiinnnngggg eeeeaaaacccchhhh ooootttthhhheeeerrrr:-
1. We know the lens formula

=

-

2. For the two lenses, we have

=

-

------ (1)

=

!
-

----- (2)
3. Adding equation (1) and (2), we have

+

=

-

+

!
-

+

=

!
-

.Here f is the equivalent focal length of the combination.
4. Thus

=

+

ii)))) FFFFooooccccaaaallll lllleeeennnnssss ooooffff ccccoooommmmbbbbiiiinnnnaaaattttiiiioooonnnn ooooffff ttttwwwwoooo lllleeeennnnsssseeeessss aaaarrrreeee ttttoooouuuucccchhhhiiiinnnngggg eeeeaaaacccchhhh ooootttthhhheeeerrrr:-
1. When two lens are separated by a distance‘d’ and its focal
lengths are f1 and f2 .
2. Then focal length,

=

+

-

22
14. Collect the information ... CCCooolllllleeecccttt ttthhheee iiinnnfffooorrrmmmaaatttiiiooonnn aaaabbbboooouuuutttt tttthhhheeee lllleeeennnnsssseeeessss aaaavvvvaaaaiiiillllaaaabbbblllleeee iiiinnnn aaaannnn ooooppppttttiiiiccccaaaallll sssshhhhoooopppp.... FFFFiiiinnnndddd oooouuuutttt hhhhoooowwww tttthhhheeee ffffooooccccaaaallll lllleeeennnnggggtttthhhh ooooffff aaaa
lllleeeennnnssss mmmmaaaayyyy bbbbeeee ddddeeeetttteeeerrrrmmmmiiiinnnneeeedddd bbbbyyyy tttthhhheeee ggggiiiivvvveeeennnn ‘‘‘‘ppppoooowwwweeeerrrr’’’’ ooooffff tttthhhheeee lllleeeennnnssss.... ((((AAAASSSS4444))))
1. The lenses available in the optical shop is below,
Glass, concave lens, convex lens photo chromic lenses, single vision lenses, sport glasses,
occupational lenses etc.
2. The focal length of a lens is determined by using the formula, Power (D) =

.
3. Here f is the focal length of a lens.
PPPPoooowwwweeeerrrr ooooffff lllleeeennnnssss iiiinnnn ddddiiiioooopppptttteeeerrrrssss TTTTyyyyppppeeee ooooffff lllleeeennnnssss FFFFooooccccaaaallll lllleeeennnnggggtttthhhh
0.25 Convex 400 cm
0.5 Convex 200 cm
-2 Concave 50 cm
-0.5 Concave -100 cm
1 Convex 100 cm
-0.25 Concave -400 cm
11115555.... CCCCoooolllllllleeeecccctttt tttthhhheeee iiiinnnnffffoooorrrrmmmmaaaattttiiiioooonnnn aaaabbbboooouuuutttt lllleeeennnnsssseeeessss uuuusssseeeedddd bbbbyyyy GGGGaaaalllliiiilllleeeeoooo iiiinnnn hhhhiiiissss tttteeeelllleeeessssccccooooppppeeee???? ((((AAAASSSS4444))))
1. Galilean telescope has one convex lens and one concave lens.
2. The concave lens serves as the ocular lens or the eyepiece, while the convex lens serves as the
object.
3. The lens are situated on either side of a tube such that focal point of the ocular lens is same as
the focal point for the objective lens.
11116666.... UUUUsssseeee tttthhhheeee ddddaaaattttaaaa oooobbbbttttaaaaiiiinnnneeeedddd bbbbyyyy aaaaccccttttiiiivvvviiiittttyyyy--2222 iiiinnnn ttttaaaabbbblllleeee-1111 ooooffff tttthhhhiiiissss lllleeeessssssssoooonnnn aaaannnndddd ddddrrrraaaawwww tttthhhheeee ggggrrrraaaapppphhhhssss ooooffff uuuu vvvvssss.... vvvv aaaannnndddd
#
$
vvvvssss....
#
%
..
((((AAAASSSS5555)))) TTTTaaaabbbblllleeee
V 70 65 60 55 50 45 40 35 30 25 20 15 12 11
u 11 11.5 12 12.5 13 13.5 14 14.5 15 16.5 20 25 50 60

23
11117777.... FFFFiiiigggguuuurrrreeee QQQQ-11113333 sssshhhhoooowwwwssss rrrraaaayyyy AAAABBBB tttthhhhaaaatttt hhhhaaaassss ppppaaaasssssssseeeedddd tttthhhhrrrroooouuuugggghhhh aaaa ddddiiiivvvveeeerrrrggggeeeennnntttt lllleeeennnnssss.... CCCCoooonnnnssssttttrrrruuuucccctttt tttthhhheeee ppppaaaatttthhhh ooooffff tttthhhheeee rrrraaaayyyy uuuupppp
ttttoooo tttthhhheeee lllleeeennnnssss iiiiffff tttthhhheeee ppppoooossssiiiittttiiiioooonnnn ooooffff iiiittttssss ffffoooocccciiii iiiissss kkkknnnnoooowwwwnnnn.... ((((AAAASSSS5555))))
11118888.... FFFFiiiigggguuuurrrreeee QQQQ-11114444 sssshhhhoooowwwwssss aaaa ppppooooiiiinnnntttt lllliiiigggghhhhtttt ssssoooouuuurrrrcccceeee aaaannnndddd iiiittttssss iiiimmmmaaaaggggeeee pppprrrroooodddduuuucccceeeedddd bbbbyyyy aaaa lllleeeennnnssss wwwwiiiitttthhhh aaaannnn ooooppppttttiiiiccccaaaallll aaaaxxxxiiiissss NNNN1N2....
FFFFiiiinnnndddd tttthhhheeee ppppoooossssiiiittttiiiioooonnnn ooooffff tttthhhheeee lllleeeennnnssss aaaannnndddd iiiittttssss ffffoooocccciiii uuuussssiiiinnnngggg aaaa rrrraaaayyyy ddddiiiiaaaaggggrrrraaaammmm.... ((((AAAASSSS5555))))
11119999.... FFFFiiiinnnndddd tttthhhheeee ffffooooccccuuuussss bbbbyyyy uuuussssiiiinnnngggg aaaa rrrraaaayyyy ddddiiiiaaaaggggrrrraaaammmm uuuussssiiiinnnngggg tttthhhheeee ppppoooossssiiiittttiiiioooonnnn ooooffff ssssoooouuuurrrrcccceeee SSSS aaaannnndddd tttthhhheeee iiiimmmmaaaaggggeeee SSSSIIII ((((AAAASSSS5555))))

24
22220000.... AAAA ppppaaaarrrraaaalllllllleeeellll bbbbeeeeaaaammmm ooooffff rrrraaaayyyyssss iiiissss iiiinnnncccciiiiddddeeeennnntttt oooonnnn aaaa ccccoooonnnnvvvveeeerrrrggggeeeennnntttt lllleeeennnnssss wwwwiiiitttthhhh aaaa ffffooooccccaaaallll lllleeeennnnggggtttthhhh ooooffff 44440000ccccmmmm.... WWWWhhhheeeerrrreeee aaaa
ddddiiiivvvveeeerrrrggggeeeennnntttt lllleeeennnnssss wwwwiiiitttthhhh aaaa ffffooooccccaaaallll lllleeeennnnggggtttthhhh ooooffff 11115555 ccccmmmm sssshhhhoooouuuulllldddd bbbbeeee ppppllllaaaacccceeeedddd ffffoooorrrr tttthhhheeee bbbbeeeeaaaammmm ooooffff rrrraaaayyyyssss ttttoooo rrrreeeemmmmaaaaiiiinnnn ppppaaaarrrraaaalllllllleeeellll
aaaafffftttteeeerrrr ppppaaaassssssssiiiinnnngggg tttthhhhrrrroooouuuugggghhhh tttthhhheeee ttttwwwwoooo lllleeeennnnsssseeeessss???? DDDDrrrraaaawwww aaaa rrrraaaayyyy ddddiiiiaaaaggggrrrraaaammmm.... ((((AAAASSSS5555))))
1. The focal length of conversing lens is 40 cm.
2. The focal length of diverging lens is 15 cm.
3. The separation between them (d) = 40-15=25 Cm
4. The diverging lens has to be placed in the focal
length of the convergent lens.
22221111.... DDDDrrrraaaawwww aaaa rrrraaaayyyy ddddiiiiaaaaggggrrrraaaammmm ffffoooorrrr tttthhhheeee ffffoooolllllllloooowwwwiiiinnnngggg ppppoooossssiiiittttiiiioooonnnnssss aaaannnndddd eeeexxxxppppllllaaaaiiiinnnn tttthhhheeee nnnnaaaattttuuuurrrreeee aaaannnndddd ppppoooossssiiiittttiiiioooonnnn ooooffff iiiimmmmaaaaggggeeee....
1)))).... OOOObbbbjjjjeeeecccctttt iiiissss ppppllllaaaacccceeeedddd aaaatttt CCCC2 2).... OOOObbbbjjjjeeeecccctttt iiiissss ppppllllaaaacccceeeedddd bbbbeeeettttwwwweeeeeeeennnn FFFF2 aaaannnndddd ooooppppttttiiiicccc cccceeeennnnttttrrrreeee PPPP.... ((((AAAASSSS5555))))
CCCCoooonnnnvvvveeeexxxx LLLLeeeennnnssss :- 1111)))).... OOOObbbbjjjjeeeecccctttt iiiissss ppppllllaaaacccceeeedddd aaaatttt CCCC2
NNNNaaaattttuuuurrrreeee:::: - RRRReeeeaaaallll aaaannnndddd iiiinnnnvvvveeeerrrrtttteeeedddd
PPPPoooossssiiiittttiiiioooonnnn:::: - FFFFoooorrrrmmmmeeeedddd aaaatttt CCCC1111 hhhhaaaavvvviiiinnnngggg ssssaaaammmmeeee ssssiiiizzzzeeee aaaassss tttthhhhaaaatttt ooooffff oooobbbbjjjjeeeecccctttt....
2222)))).... OOOObbbbjjjjeeeecccctttt iiiissss ppppllllaaaacccceeeedddd bbbbeeeettttwwwweeeeeeeennnn FFFF2 aaaannnndddd ooooppppttttiiiicccc cccceeeennnnttttrrrreeee PPPP....
NNNNaaaattttuuuurrrreeee:::: - VVVViiiirrrrttttuuuuaaaallll PPPPoooossssiiiittttiiiioooonnnn: SSSSaaaammmmeeee ssssiiiiddddeeee ooooffff tttthhhheeee oooobbbbjjjjeeeecccctttt,,,, mmmmaaaaggggnnnniiiiffffiiiieeeedddd..
CCCCoooonnnnccccaaaavvvveeee LLLLeeeennnnssss:-1111)))).... OOOObbbbjjjjeeeecccctttt iiiissss ppppllllaaaacccceeeedddd aaaatttt CCCC2
NNNNaaaattttuuuurrrreeee:-VVVViiiirrrrttttuuuuaaaallll aaaannnndddd eeeerrrreeeecccctttt
PPPPoooossssiiiittttiiiioooonnnn:-SSSSiiiizzzzeeee aaaassss tttthhhhaaaatttt ooooffff oooobbbbjjjjeeeecccctttt,,,, ddddiiiimmmmiiiinnnniiiisssshhhheeeedddd..

25
2). Object 222)))... OOObbbjjjeeecccttt iiiissss ppppllllaaaacccceeeedddd bbbbeeeettttwwwweeeeeeeennnn FFFF2 aaaannnndddd ooooppppttttiiiicccc cccceeeennnnttttrrrreeee PPPP....
NNNNaaaattttuuuurrrreeee: - Virtual, erect PPPPoooossssiiiittttiiiioooonnnn: Same side of the object, diminished.
22222222.... HHHHoooowwww ddddoooo yyyyoooouuuu aaaapppppppprrrreeeecccciiiiaaaatttteeee tttthhhheeee ccccooooiiiinnnncccciiiiddddeeeennnncccceeee ooooffff tttthhhheeee eeeexxxxppppeeeerrrriiiimmmmeeeennnnttttaaaallll ffffaaaaccccttttssss wwwwiiiitttthhhh tttthhhheeee rrrreeeessssuuuullllttttssss oooobbbbttttaaaaiiiinnnneeeedddd bbbbyyyy aaaa rrrraaaayyyy
ddddiiiiaaaaggggrrrraaaammmm iiiinnnn tttteeeerrrrmmmmssss ooooffff bbbbeeeehhhhaaaavvvviiiioooouuuurrrr ooooffff iiiimmmmaaaaggggeeeessss ffffoooorrrrmmmmeeeedddd bbbbyyyy lllleeeennnnsssseeeessss???? ((((AAAASSSS6666))))
1. We are getting exactly same type of image as prescribed in ray diagrams by lenses.
2. So, everyone should have to appreciate this and the work of scientists who made a lot of effort on
ray diagrams successfully in getting same type of images as obtained from experiments.
22223333.... FFFFiiiinnnndddd tttthhhheeee rrrreeeeffffrrrraaaaccccttttiiiivvvveeee iiiinnnnddddeeeexxxx ooooffff tttthhhheeee ggggllllaaaassssssss wwwwhhhhiiiicccchhhh iiiissss aaaa ssssyyyymmmmmmmmeeeettttrrrriiiiccccaaaallll ccccoooonnnnvvvveeeerrrrggggeeeennnntttt lllleeeennnnssss iiiiffff iiiittttssss ffffooooccccaaaallll lllleeeennnnggggtttthhhh iiiissss eeeeqqqquuuuaaaallll
ttttoooo tttthhhheeee rrrraaaaddddiiiiuuuussss ooooffff ccccuuuurrrrvvvvaaaattttuuuurrrreeee ooooffff iiiittttssss ssssuuuurrrrffffaaaacccceeee.... ((((AAAASSSS7777)))) ((((AAAAnnnnssss:::: 1111....5555)
1. The given lens is a symmetrical convergent lens. i.e. R1=R2=R and f=R.
2. Refractive index of air is 1. Let μ be the refractive index of the lens.
3.

= (μ-1) [

-

] ⟹

= (μ-1) [

-

(
)
]
⟹

= (μ-1) [

+

(
)
]
⟹

= (μ-1) [

]
⟹ 2(μ-1) =1
⟹ μ-1 =

⟹ μ = 1+

⟹ μ =

⟹ μ = 1.5
∴ The refractive index of the glass is 1.5
22224444.... FFFFiiiinnnndddd tttthhhheeee rrrraaaaddddiiiiiiii ooooffff ccccuuuurrrrvvvvaaaattttuuuurrrreeee ooooffff aaaa ccccoooonnnnvvvveeeexxxxoooo ––ccccoooonnnnccccaaaavvvveeee ccccoooonnnnvvvveeeerrrrggggeeeennnntttt lllleeeennnnssss mmmmaaaaddddeeee ooooffff ggggllllaaaassssssss wwwwiiiitttthhhh rrrreeeeffffrrrraaaaccccttttiiiivvvveeee iiiinnnnddddeeeexxxx
nnnn====1111....5555 hhhhaaaavvvviiiinnnngggg ffffooooccccaaaallll lllleeeennnnggggtttthhhh ooooffff 22224444ccccmmmm.... OOOOnnnneeee ooooffff tttthhhheeee rrrraaaaddddiiiiiiii ooooffff ccccuuuurrrrvvvvaaaattttuuuurrrreeee iiiissss ddddoooouuuubbbblllleeee tttthhhheeee ooootttthhhheeeerrrr....
((((AAAAnnnnssss::::RRRR1====6666ccccmmmm,,,,RRRR2====11112222ccccmmmm)))) ((((AAAASSSS7777))))
GGGGiiiivvvveeeennnn :- Refractive index of the glass, n=1.5
Focal length , f= 24
Let the radius of curvature of convex surface = R1
Let the radius of curvature of concave surface = R2 = 2R1

= (μ-1) [

-

] ⟹

)
= (1.5-1) [

-

]

26
⟹

)
= (0.5) [

] ⟹

)
= (0.5) [

]
⟹

=

)-..
⟹2R1 =24 x 0.5 ⟹ R1 =
) ..

=6 Cm
R2 = 2R1 = 2 x 6 =12 Cm
22225555.... TTTThhhheeee ddddiiiissssttttaaaannnncccceeee bbbbeeeettttwwwweeeeeeeennnn ttttwwwwoooo ppppooooiiiinnnntttt ssssoooouuuurrrrcccceeeessss ooooffff lllliiiigggghhhhtttt iiiissss 22224444ccccmmmm ....WWWWhhhheeeerrrreeee sssshhhhoooouuuulllldddd aaaa ccccoooonnnnvvvveeeerrrrggggeeeennnntttt lllleeeennnnssss wwwwiiiitttthhhh aaaa ffffooooccccaaaallll
lllleeeennnnggggtttthhhh ooooffff ffff====9999ccccmmmm bbbbeeee ppppllllaaaacccceeeedddd bbbbeeeettttwwwweeeeeeeennnn tttthhhheeeemmmm ttttoooo oooobbbbttttaaaaiiiinnnn tttthhhheeee iiiimmmmaaaaggggeeeessss ooooffff bbbbooootttthhhh ssssoooouuuurrrrcccceeeessss aaaatttt tttthhhheeee ssssaaaammmmeeee ppppooooiiiinnnntttt???? ((((AAAASSSS7777))))
GGGGiiiivvvveeeennnn :- Focal length, f = 9 Cm
Suppose x is the distance of the first object from the lens.
Let u =y and v =-x
Lens formula

=

-

⟹

/
=

0
-

⟹

0
=

/
-

---(1)
For the second object O2 where image is also formed at I.
Let u = -(24-x) v = -y
Lens formula

/
=

() )
-

0
⟹

0
=

() )
-

/
---(2)
From (1) and (2), we have

() )
-

/
=

/
-

⟹ x2-24x+108 = 0
Solving for x gives x= 18 Cm and x= 6 Cm
∴ Lens should be placed 18 cm and 6 cm to the right of the first object.
22226666.... SSSSuuuuppppppppoooosssseeee yyyyoooouuuu aaaarrrreeee iiiinnnnssssiiiiddddeeee tttthhhheeee wwwwaaaatttteeeerrrr iiiinnnn aaaa sssswwwwiiiimmmmmmmmiiiinnnngggg ppppoooooooollll nnnneeeeaaaarrrr aaaannnn eeeeddddggggeeee.... AAAA ffffrrrriiiieeeennnndddd iiiissss ssssttttaaaannnnddddiiiinnnngggg oooonnnn tttthhhheeee eeeeddddggggeeee....
DDDDoooo yyyyoooouuuu ffffiiiinnnndddd yyyyoooouuuurrrr ffffrrrriiiieeeennnndddd ttttaaaalllllllleeeerrrr oooorrrr sssshhhhoooorrrrtttteeeerrrr tttthhhhaaaannnn hhhhiiiissss uuuussssuuuuaaaallll hhhheeeeiiiigggghhhhtttt???? WWWWhhhhyyyy???? ((((AAAASSSS7777))))
1. Let the actual height of the person be ‘x’ feet.
2.

=

.
3.
=

4. Apparent height of the man = 1.33XActual height
= 1.33 times of the actual height of the person.
5. Hence, you find your friend is taller his usual height.

-
!
YYYYoooouuuurrrr hhhheeeellllpppp aaaassssssssiiiissssttttssss yyyyoooouuuu;;;; ffffoooorrrreeeevvvveeeerrrr--SSSShhhhaaaaddddeeee rrrreeeessssttttssss uuuunnnnddddeeeerrrr ttttrrrreeeeeeeessss oooonnnnllllyyyy....

27
ChapteCCChhhaaapppttteeerrrr –– 7
HHHHuuuummmmaaaannnn eeeeyyyyeeee aaaannnndddd CCCCoooolllloooouuuurrrrffffuuuullll wwwwoooorrrrlllldddd
1111.... HHHHoooowwww ddddoooo yyyyoooouuuu ccccoooorrrrrrrreeeecccctttt tttthhhheeee eeeeyyyyeeee ddddeeeeffffeeeecccctttt,,,, MMMMyyyyooooppppiiiiaaaa???? ((((AAAASSSS1111))))
MMMMyyyyooooppppiiiiaaaa: - 1. The defect in which people cannot see objects beyond far point is called Myopia.
2. Myopia is also known as ‘near sightednesses.
CCCCoooorrrrrrrreeeeccccttttiiiioooonnnn: - 1. Eye lens can form clear image on retina, when an object is placed between far
point and point of least distance of clear vision.
2. If we could able to bring the image of the object kept beyond far point , between
the far point and the point of least distance of clear vision using a lens, this
image act as an object for eye lens.
3. This can be possible only when a concave lens is used.
2222.... EEEExxxxppppllllaaaaiiiinnnn tttthhhheeee ccccoooorrrrrrrreeeeccccttttiiiioooonnnn ooooffff tttthhhheeee eeeeyyyyeeee ddddeeeeffffeeeecccctttt,,,, HHHHyyyyppppeeeerrrrmmmmeeeettttrrrrooooppppiiiiaaaa????
HHHHyyyyppppeeeerrrrmmmmeeeettttrrrrooooppppiiiiaaaa: - 1.The defect in which people cannot see objects before near point is called
Hypermetropia.
2. Hypermetropia is also known as ‘farsighted nesses.
CCCCoooorrrrrrrreeeeccccttttiiiioooonnnn: - 1. Eye lens can form clear image on retina when any object is placed beyond near
point.
2. To correct the defect of hypermetropia, we need to use a lens which forms image
of object beyond near point between near point (H) and least distance of clear
vision (L).
3. This can be possible only when a double convex lens is used.
3333.... HHHHoooowwww ddddoooo yyyyoooouuuu ffffiiiinnnndddd eeeexxxxppppeeeerrrriiiimmmmeeeennnnttttaaaallllllllyyyy tttthhhheeee rrrreeeeffffrrrraaaaccccttttiiiivvvveeee iiiinnnnddddeeeexxxx ooooffff mmmmaaaatttteeeerrrriiiiaaaallll ooooffff aaaa pppprrrriiiissssmmmm ((((AAAASSSS1111????)
AAAAiiiimmmm: - To find the refractive index of the prism.
MMMMaaaatttteeeerrrriiiiaaaallll rrrreeeeqqqquuuuiiiirrrreeeedddd: - Prism, piece of white chart of size 20x20 cm, pencil, pins, scale protractor.

28
PPPPrrrroooocccceeeedddduuuurrrreeee: -
1. Place the prism on the white chart and draw the boundary lines by using a pencil.
2. Remove the prism and name the vertices as P, Q and R.
3. Calculate the angle of the prism (A=600) and noted in your book.
4. Now fix two pins vertically on the line at points A and B as shown in the figure.
5. Observe the other side of the prism and fix another two pins such that AB and CD appear
to lie along the straight line.
6. The angle of incident and angle of emergent are intersect at one point is called angle of
deviation (D).
7. The refractive index of a prism is calculated by using the formula,
n =
(

)
(

)
4444.... EEEExxxxppppllllaaaaiiiinnnn tttthhhheeee ffffoooorrrrmmmmaaaattttiiiioooonnnn ooooffff RRRRaaaaiiiinnnnbbbboooowwww???? ((((AAAASSSS1111))))
FFFFoooorrrrmmmmaaaattttiiiioooonnnn ooooffff RRRRaaaaiiiinnnnbbbboooowwww: - 1. The beautiful colours of rainbow are due to dispersion of the sunlight
by millions of tiny water droplets.
2. Let us consider a case of an individual water drop.
3. The ray of sunlight enters the drop near its top surface.
4. At this first refraction, the white light is dispersed into its spectrum of colours, violet being
deviated the most and red the least.
5. Reaching the opposite side of the drop, each colour is reflected back into the drop because of
total internal reflection.
6. If you see at an angle between 400 and 420, you will observe remaining colours of VIBGYOR.

29
5. Explain briefly the reason for the Blue 555... EEExxxppplllaaaiiinnn bbbrrriiieeeffflllyyy ttthhheee rrreeeaaasssooonnn fffooorrr ttthhheee BBBllluuueee ooooffff tttthhhheeee sssskkkkyyyy???? ((((AAAASSSS1111))))
1. The reason for the appearance of sky in blue colour is due to the phenomenon of scattering of
sunlight by the atoms or molecules present in the sky.
2. Our atmosphere contains Nitrogen and Oxygen.
3. When sun rays falls on these atoms, the size of these molecules are comparable to the
wavelength of blue light.
4. These molecule act as scattering centers for scattering of Blue light.
5. So the sky appears to be Blue in colour.
6666.... EEEExxxxppppllllaaaaiiiinnnn ttttwwwwoooo aaaaccccttttiiiivvvviiiittttiiiieeeessss ffffoooorrrr tttthhhheeee ffffoooorrrrmmmmaaaattttiiiioooonnnn ooooffff aaaarrrrttttiiiiffffiiiicccciiiiaaaallll rrrraaaaiiiinnnnbbbboooowwww???? ((((AAAASSSS1111))))
AAAAccccttttiiiivvvviiiittttyyyy--1: - 1. Take a prism and place it in between the light source and white wall.
2. Sent a light source such that the rays are falls on the prism through the narrow
slit of a wooden plank.
3. Switch on the light. Adjust the height of the prism such that the light falls on one
of the lateral surfaces.
4. We observed that the emergent light forms an artificial rainbow on the wall.
AAAAccccttttiiiivvvviiiittttyyyy--2: -
1. Take a tray and fill it with water.
2. Place a mirror in the water such that it makes an angle to the water surface.
3. Now focus white light on the mirror through the water as shown in figure.
4. Try to obtain colour on a white card board sheet kept above the water surface.
5. We observe that a white ray of light splits into certain different colours called VIBGYOR.

Physics study material (1)

Recommended

Recommended

More Related Content

Similar to Physics study material (1)

Similar to Physics study material (1) (20)

Recently uploaded

Recently uploaded (20)

Physics study material (1)