Refraction of light -1 By R k Chaudhary Faculty of M A E S PGT Physics

1. PHYSICS
REFRACTION OF LIGHT
Part-I
CLASS- 10th
By R K Chaudhari
rkchaudhary222@gmail.com
Contact no: 8960502268

2. REFRACTION OF LIGHT
A Pencil partially immersed in water appears bent. The floor of a
swimming pool appears raised for an observer on the diving board.
The sun is seen a little before it rises and also for a short while after
it sets.
Raghvendra kumar chaudhary
rkchaudhary222@gmail.com
Contact no: 8960502268

3. Medium- Refers to any substance on material from which light pass
Medium is two type
1. Rarer Medium
2. Denser Medium
Rarer Medium- which has less density and speed of light is more in it.
Denser Medium- which has more density and speed of is low
because particle very near (Water).
Refraction – The bending of light ray when it passes from one
medium to another medium is called refraction.
Incident ray- The ray that strikes the surface
Point of incidence- Point where incident ray strikes the surface
Refracted ray- The ray that changes its path when it travels from onn
medium to another
Normal ray- The perpendicular drawn to point of incidence.
Raghvendra kumar chaudhary
rkchaudhary222@gmail.com
Contact no: 8960502268

4. Laws of refraction-
1. Incident ray normal ray & refracted ray all lie on same plane of
paper
2. The ratio of sine of angle of incidence to sine of angle of
refraction is always constant for particular pair of media.
Sin i/ Sin r = constant
Refractive Index- it is the speed of light in vaccum/ speed of light in
given medium
Or
The ratio of sine of angle of incidence to sine of angle of refraction is
always constant for particular pair of media
ang- Refractive index of glass with to air
Raghvendra kumar chaudhary
rkchaudhary222@gmail.com
Contact no: 8960502268

5. n = c/ v
where n is refractive index
c is velocity of light in vacuum and
v is velocity of light in substance
Sin i / sin r = ang
n21 – refractive index of medium 2 wrt to medium 1.
Sin I / sir r = nga = ang -glass with respect to air
Q - The refractive index of glass is 1.5. The speed of light in vaccum is
3x108 m/s. calculate the speed of light in glass.
Given refractive index of glass is 1.5
Speed of light in vaccum is 3x108m/s
Velocity of light in glass vg = ?
Refractive index of glass with respect to air tor vaccum is
vg = c/ng
=3x108 /1.5
= 2x108 m/s
Raghvendra kumar chaudhary
rkchaudhary222@gmail.com
Contact no: 8960502268

6. Practice problem
1- A ray of light travels from water to glass. The angle of incidence
is 40 degree. Calculate the angle of refraction and the deviation
produced.
Given ng = 1.5
nw = 1.3
2-A ray of light enters a diamond from air. If the refractive index of
diamond is 2.42, by what percent does the speed of light reduce on
entering the diamond?
3-A ray of light travelling in air falls on the surface of a transparent
slab. The ray makes an angle of 45 degree with the normal to the
surface. Find the angle made by the refracted ray with the normal
within the slab. Refractive index of the material of the slab =1.414
4- The speed of light in an unknown medium is 1.76 × 108 m/s.
Calculate the refractive index of the medium.
5- In the following diagram angle of incidence is?
Raghvendra kumar chaudhary
rkchaudhary222@gmail.com
Contact no: 8960502268

7. 6- what do you mean by n31?
7-what is refractive index and its unit?
8-what is medium?
9-what is refraction of light give any two example?
10-what is shadow?
Raghvendra kumar chaudhary
rkchaudhary222@gmail.com
Contact no: 8960502268