AMU - Physics - 1999

AMU –PAST PAPERSPHYSICS- UNSOLVED PAPER - 1999

SECTION – I Single Correct Answer Type  There are five parts in this question. Four choices are given for each part and one of them is correct. Indicate you choice of the correct answer for each part in your answer-book by writing the letter (a), (b), (c) or (d) whichever is appropriate

01 Problem The substance which shows no elastic after effect is : a. Silk b. Rubber c. Copper d. Quartz

02 Problem A ball of mass m falls vertically to the ground from a height h1and rebound to a height h2. The change in momentum of the ball on striking the ground is : a. m 2(h1 h2 ) b. n 2g(m1 m2 ) c. mg (h1-h2) d. m( 2gh1 2gh2 )

03 Problem In 1.0 second a particle goes from point A to point B moving in a semicircle of radius 1.0 m figure. The magnitude of the average velocity is : a. Zero b. 1.0 m/s c. 2.0 m/s d. 3.14 m/s

04 Problem In the Young’s double slit experiment . If the width of the slits are in the ratio 4:9. then the ratio of intensity at maxima to the intensity at minima will be : a. 9:4 b. 25:1 c. 81:16 d. 169:25

05 Problem If the earth were the cease rotating about its own axis. The increase in the value of g in C.G.S. system at a place of latitude of 450will be: a. 2.68 b. 1.68 c. 3.36 d. 0.34

06 Problem A transformer is employed to reduce 220 volt to 11 volts. The primary draws a current of 5 A and the secondary 90 A. The efficiency of the transformer is: a. 90% b. 45% c. 75% d. 20%

07 Problem A transistor has an a = 0.95. It has change in emitter current of 1000 mA then the change in collector current is: a. 95 mA b. 99.05 mA c. 100.96 mA d. 100 mA

08 Problem The resistance of a wire at 20 C is 20 ohms and at 500 C is 60 60 ohms. At which temperature its resistance will be 25 ohm? a. 800 C b. 700C c. 600 C d. 500 C

09 Problem Electron can not be constituent of the nueleus because a. The electron is a negatively charged particle b. The Compton of wavelength of electron is larger than the size of nucleus c. The mass of the electron is very small as compred to the mass of the neutron or proton d. None of these

10 Problem Energy E and frequency v of a photon is correctly represented by: a. b. c. d.

11 Problem The de Broglie wavelength of thermal neutron at a temperature T K is: a. 3MKTC h b. 3MT h c. 2mKT h d. 2MKT

12 Problem A man in a balloon rising vertically with an acceleration of 4.9m/s2 releases a ball 2 sec after the balloon is let go from the ground. The greatest height above the ground reached by the ball is: (g = 9.8 m/s2) a. 24.7 m b. 7.35 m c. 28.4 m d. 14.7 m

13 Problem A body of mass M at rest explodes into three masses, two of which are of mass m , each are thrown off in perpendicular direction with velocity 3 m/s and 4 4 m/s respectively the third piece will be thrown off with a velocity of: a. 3 m/s b. 2.5 m/s c. 4.5 m/s d. 9 m/s

14 Problem A wet open umbrella is held vertical and whirled about the handle at a uniform rate of 21 revolution in 44 seconds. If the rim of the umbrella is a circle of 1 m in diameter and the height of the rim above the floor is 4.9 m. The angular speed of the umbrella is: a. 2.5 rad/sec b. 1 rad/sec c. 1.5 rad/sec d. 3 rad/sec

15 Problem A current of I amp flows through a square loop of wire of side a metre. The magnetic induction at the centre of square loop will be : a. 2 2 0i a b. 2 0i 2 a 2 0 i c. 2 a 0 i d. 2 2 a

16 Problem One milliwatt of light of wavelength 4560 Å is incident on a caesium surface. The photoelectric current produced, if the quantum efficiency of the surface for photoelectric emission is only 0.5%, will be : a. 5.8 x 10-6 amp b. 0.92 x 10-6 amp c. 2.84 x 10-6 amp d. 1.84 x 10-6 amp

17 Problem The value of inductance which should be connected in series with a capacitance of 0.5 , resistance of 10 ohm and an A.C source of 50 cps so that the power factor of the circuit is unity, will be : a. 20.28 H b. 10.13 H c. 15.26 H d. 25.28 H

18 Problem Two capacitors of capacitances 8 and 2 are connected in series across a 100 volt D.C. supply. Now if the supply voltage is removed and the capacitors are then connected in parallel. The final charge on each capacitor will be : a. 2.56 x 10-4 C, 6.4 x 10-5 b. 3.56 x 10-4 C, 7.4 x 10-5 C c. 1.4 x 10-4 C, 5.4 x 10-5 C d. none of these

19 Problem The amount of work done to increase the temperature of one mole of an ideal gas by 300. if it is expanding under the condition V T 2/3 , will be : a. 83 J b. 166 J c. 106 J d. 16.6 J

20 Problem How many calories of heat will approximately be developed in a 210 watt electric bulb in 5 minutes? a. Zero b. 63000 c. 1050 d. 15000

21 Problem In the following circuit 5 resistor developes 10.25 cal/s due to a current flowing through it. The heat developed in 2 resistance: a. 7.31 cal b. 3.65 cal c. 8.31 cal d. 14.32 cal

22 Problem Calculate the current through the battery and through a resistance of 6 in the given circuit: a. 2.66 amp, 2 amp b. 1.33 amp, 1 amp c. 0.66 amp, 05 amp d. none of these

23 Problem Two long parallel wires carrying equal current separated 1 m, exert a force of 2x10-7 N/m on one another. The current flowing through them will be : a. 1.0 A b. 2.2 amp c. 0.5 amp d. 2 x 10-7 amp

24 Problem Two short magnets are placed on a piece of cork which floats on water. The magnets are so placed, bisects the axis of 9ther at right angles. Then the cork : a. Has neither translational nor rotational motion b. Has translational as well as rotational motion c. Moves along straight line d. Rotates only

25 Problem A paramagnetic substance of susceptibility 3x10-4 is placed in a magnetic field of 4x10-1 Am-1 . then intensity of magnetization is : a. 12 b. 1.33 x 108 c. 0.75 x 10-8 d. none of these

26 Problem A fish looking up through the water sees the out side world contained in a circular horizon. If the refractive index of water is 4 and the fish is 12 cm below 3 the surface. The radius of circle is : 12 x 3 a. 7 cm b. 12 x 5 cm 3 c. 12 x 3 x 7 cm d. 12 x 3 x 5 cm

27 Problem 4 Two immiscible liquid of refractive indices 1.5 and 3 are filled in a glass jar each of height 6 cm. A light of source S is at the bottom of the jar. The apparent depth of light source will be : a. 12.5 cm b. 17 cm c. 12 cm d. 8.5 cm

28 Problem 125 Water drops of equal radius and equal capacitance C coalesce to form a single drop of capacitance C coalesce to form a single drop of capacitance C’. The relation between C and C’ is : a. C’ = 5 C C b. C’ = 125 C c. C 5 d. C’ = 125 C

29 Problem In a circuit shown two capacitors have identical geometry. But a material of dielectric constant 3 is present between the plates of B. If a battery of emf 10V is connected across the combination the potential difference across S and B will be respectively : a. 7.5 V, 2.5 V b. 8.5 V, 3.5 V c. 5 V, 3.0 V d. none of these

30 Problem Ten tuning forks are arranged in increasing order of frequency in such a way that any two nearest forks produce 4 beats/sec. The highest frequencies is twice that of the lowest possible, lowest and highest frequencies are : a. 36, 72 Hz b. 22, 44 Hz c. 50,100 Hz d. 40, 80 Hz

31 Problem The equation of progressive wave is y = 2 sin (o.5x + 200t) (x,y in meter). The amplitude and velocity of wave respectively are : a. 2 cm, 100 cm/sec b. 2 cm, 0.5 cm/sec 3 c. 2 cm, 400 cm/sec d. 0.2 cm, 200 cm/sec

32 Problem The radius of earth’s orbit is made one fourth, the duration of a year will become : 1 a. 4 times 1 b. 8 times c. 4 times d. 8 times

33 Problem A man is sitting in a boat which is floating on a pond. If the man drinks some water from the pond, the level of water in the pond : a. Man decrease or increase dependial on the weight of the man b. Remains unchanged c. Increases d. Decreases

34 Problem In an interference pattern produced by the identical coherent sources of monochromatic light, the intensity at the site of central maxima is I. The intensity at the same spot when either of the two slits is closed is I0. We must have : a. I = 4I0 b. I and I0 are related c. I = 2I0 d. I = I0

35 Problem Two lenses of power + 12 and – 2 diopters are placed in contact. What will be the focal length of combination ? a. 8.33 cm b. 16.6 cm c. 12.5 cm d. 10 cm

36 Problem The focal length of the objective and eye piece of a telescope are respectively 200 cm and 5 cm. The maximum magniflying power of the telescope will be : a. -100 b. - 60 c. - 48 d. - 40

37 Problem A gas is compressed at a constant pressure of 50 N/m2 from a volume of 10 m3 to a volume of 4 m3. Energy of 100 joule is thus added to the gas by heating Its internal energy is : a. Decreased by 200 J b. Increased by 100 J c. Increased by 100 J d. Increased by 400 J

38 Problem The wavelength of maximum energy released during an atomic explosion was 2.93 x 10-10 m. the maximum temperature attained must be, (Weins constant = 2.93 x 10-3 mK): a. 5.86 x 107 K b. 10-13 K c. 10-7 K d. 107 K

39 Problem Which one of the following is the best observer of thermal radiation : a. Lamp black b. White cloth c. Quartz d. Flint glass

40 Problem Two metallic blocks A and B of thermal conductivities 4 K and K are connected as shown in the figure. The length of the blocks are L and respectively, then equivalent thermal conductivity of combination of two blocks is : a. 2 K b. 9 K 5 c. 2 K d. 3 K

41 Problem The least velocity required to throw a body away from the surface of a planet, so, that it may not return is (radius of the planet is 6.4 x 106 m, g = 9.8 m/s2) a. 11.2 x 103 m/sec b. 15.0 x 103 m/sec c. 12.8 x 103 m/sec d. 9.8 x 103 m/sec

42 Problem A body of mass 2 kg is released at the top of smooth inclined plane having inclination 300. It takes 3 second to reach the bottom. If the inclination is doubled keeping same height (i.e., made 600), the time taken will be : a. 1.5 sec b. 3 sec c. 3 sec d. 3 3 sec

43 Problem A ball is dropped from the top of building at the same instant another ball is thrown vertically upwards from the ground level the ball collide 2 second later. The height of the building is : a. 72 m b. 54 m c. 18 m d. 36 m

44 Problem A projectile can have the same range for two angle of projection. If h1 and h2 are maximum heights when the range in the two case is R, then the relation between R, h1 and h2 will be a. R = 4 h1 h2 b. R = 2 h1 h2 c. R = 2h1 h2 d. R = h1 h2

45 Problem a b The potential energy of particle in a certain field is given by U where r2 r a, and b are positive constants and r is the distance from the centre of the filed. The distance of the particle in the stable equilibrium position is : 2a a. - b 2a b. b a c. b a d. b

46 Problem A gun weighing 5 kg fires a bullet of mass 10-2 kg with a speed of 5 x 102 m/s. What is the kinetic energy of the bullet and gun will respectively ? a. 1.25 x 103 J, 2.5 J b. 2.25 x 103 J, 3.5 J c. 0.25 x 103 J, 1.5 J d. none of these

47 Problem The maximum wavelength of radiation that can produce photoelectric effect in a certain metal is 200 n m. The maximum Kinetic Energy acquired by the electrons due to radiations of wavelength 100 nm will be : a. 200 eV b. 100 eV c. 6.2 eV d. 12.4 eV

48 Problem Light of frequency 5 v0 fall on a photosensitive surface of the solid frequency v0. The velocity of emitted electrons is 4 x 105 m/s. If now light of frequency 9v0 is incident on the surface, then velocity of electron will become : a. 5.64 x 105 m/s b. 7.2 x 105 m/s c. 8 x 105 m/s d. 2 x 105 m/s

49 Problem A star initially has 1040 deuterons. It produces energy na the process 2 + 1H2 1H3 + p 1H 2 + 1H3 2H4 + n 1H If the average power radiated by the star is 1016 =2.014 amu, M(n) = 4.001 amu, M(m) = 1.008 amu M(He4) = 4.001 amu the deuteron supply of the star is exhausted in the time of the order of the : a. 1016 sec b. 1012 sec c. 106 sec d. 108 sec

50 Problem The type of bonding in silicon crystal is : a. Vander walls b. Covalent c. Ionic d. Metallic

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AMU - Physics - 1999

by Vasista Vinuthan

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