Phy

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Physics 1. The velocity with which a projectile must be fired so that it escapes earth's gravitation does not depend on (A) Mass of the earth (B) Mass of the projectile (C) Radius of the projectile's orbit (D) Gravitational constant ans:B

2. The maximum distance upto which TV transmission from a TV tower of height h can be received is proportional to-

(A) h1/2 (B) h (C) h3/2 (D) h2 ans:A

3. In short wave communication waves of which of the following frequencies will be reflected back by the ionospheric layer having electron density 1011 per m-3? (A) 2 MHz (B) 10 MHz (C) 12 MHz (D) 18 MHz ans:B

4. When a monochromatic point source of light is at a distance of 0.2 m from a photocell, the cut-off voltage and the

current are respectively Vo = 0.6 volt and Is = 18.0 mA. If the same source is placed 0.6 m away from the photocell, (A) Stopping potential Vo = 0.2 volt and saturation current Is = 18.0 mA (B) Stopping potential Vo = 0.6 volt and saturation current Is = 18.0 mA (C) Stopping potential Vo = 0.6 volt and saturation currenl Is = 2.0 mA (D) Stopping potential Vo = 0,2 volt and saturation current Is=2.0mA ans:C 5. When light of wavelength 300 nm (nanometre) falls on a photoelec' tric emitter, photoelectrons are just liberated. (A) 1 : 2 (B) 2 : 1 (C) 4 : 1 (D) 1 : 4 ans:B

6. A transformer is used to light a 140 watt, 24 volt lamp from 240 V A.C. mains. The current in the mains cable is 0 (A) 48% (B) '63.8% (C) 83.3% (D) 90% Ans:C

7. A solenoid has 2000 turns wound over a length of 0.30 m. The area of its cross-section is 1.2 x 10- 3 m2. Around (8) 4.8 volt (C) 4.8 x 10-1 volt (D) 4.8 x 10- 2 volt Ans:D

8. If a planet of given density were: made larger (keeping its density unchanged) its force of attraction for an object o (A) Increase in mass (B) Increase in radius (C) Both affect the attraction equally

(D) None of the above Ans:B 9. A laser beam is used for carrying out surgery because it (A) Is highly monochromatic (B) Is highly coherent (C) Is highly directional (D) Can be sharply focussed ans:B

10. A proton is about 1840 times heavier than an electron. When it is accelerated by a potential difference of 1 kV, i energy will be(A) 1840 keV (B) 1/1840 keV (C) 1 keV (D) 920 keV ans:C 11. An electric dipole placed in a nonuniform electric field experiences (A) Both, a torque and a net force (B) Only a force but no torque (C) Only a torque but no net force (D) No torque and no net force Ans:A

12. A neutron makes a head-on elastic collision with a stationary deuteron. The fractional energy loss of the neutron is (A) 16/81 (C) 8/27 (B) 8/9

(D) 2/3 ans:B 13. The motion of planets in the solar system is an example of the conservation of(A) Mass (B) Linear momentum (C) Angular momentum (D) Energy ans:C 14. Two small drops of mercury,each of radius R, coalesce to form a single large drop. The ratio of the total surface energies before and after the change is(A) 1: 21/3 (B) 21/3: 1 (C) 2: 1 (D) 1 : 2 ans:B

15. A double slit experiment is performed with light of wavelength 500 nm. A thin film of thickness 2 μm and refractiv (A) Remain unshifted (B) Shift downward by nearly two fringes (C) Shift upward by nearly two fringes (D) Shift downward by 10 fringes ans:C 16. If an electron and a photon propagate in the form of waves having the same wavelength, it implies that they have the same(A) Energy (B) Momentum (C) Velocity

(D) Angular momentum ans:B 17. Characteristic X-rays are produced due to(A) Transfer of momentum in collision of electrons with target atoms (B) Transition of electrons from higher to lower electronic orbits in an atom (C) Heating of the target (D) Transfer of energy in collision E)f electrons with atoms in the target Ans:B 18. An astronaut is looking down on earth's surface from a space shuttle at an altitude of 400 km. Assuming that the astronaut's pupil diameter is 5 mm and the wavelength of visible light is 500 nm. The astronaut will be able to resolve linear objects of the size of about(A) 0.5 m (B) 5 m (C) 50 m (D) 500 m ans:C 19. An earthquake generates both transverse (8) and longitudinal (P) sound waves in the earth. The speed of 8 waves is about 4.5 km/s and that of P waves is about 8.0 km/s. A seismograph records P and 8 waves from an earthquake. The first P wave arrives 4.0 min before the first 8 wave. The epicenter of the earthquake is located at a distance of about(A) 25 km (8) 250 km (C) 2500 km (D) 5000 km ans:C 20. Using mass (M), length (L), time (T) and current (A) as fundamental quantities, the dimension

of permeability is(A) M-1LT-2 A (B) ML 2T-2 A-1 (C) ML T-2 A-2 (D) ML T-1 A-1 ans:C

21. Moment of inertia of a uniform disc about a diameter is I. Its moment of inertia about an axis perpendicular to its (A) 51 (C) 41

(B) 31 (D) 61

Ans:D

22. Solar radiation emitted by sun correspond to that emitted by a black body at a temperature of 6000K. Maximum emitted at wavelength of 4~00 A. If the sun were to cool down from 6000K to 3000K, then the peak intensity of emit (A) 4800 A0 (B) 9600 A0 (C) 2400 A0 (D) 19,200 A0 Ans:B

23. An ideal gas heat engine operates in a Carnot cycle between 227°C and 127°C. It absorbs 6 x 104 cal at the hig (A) 4.8 x 104 cal (B) 1.2 x 104 cal (C) 3.5 x 104 cal (D) 1.6 x 104 cal Ans:B

24. In the experiment for the determination of elm of electron by the Thomson method, elecl and magnetic fields are (A) Parallel and both are perpendicular to the motion of electron (B) Both mutually parallel and also parallel to the motion of the electron (C) Both mutually perpendicular and also perpendicular the motion of electron (D) Both mutually perpendicular and have no relation with motion of the electron

Ans:C 25. Blue colour of sky is due to(A) Interference (B) Scattering of light (C) Dispersion of light (D) Sun emits more of blue' Ans:B

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does not depend on

l, the cut-off voltage and the saturation m away from the photocell, then-

electrons are just liberated. For another emitter however, light of 600 nm wave length is sufficient for creating photoemission. What is the ram

rrent in the mains cable is 0.7 amp. The efficiency of the transformer is-

n is 1.2 x 10- 3 m2. Around its central section a coil of 300 turns is wound. If an initial current of 2A in the solenoid is reversed in 0.25 see, t

e of attraction for an object on its surface would increase because of increased mass of the planet but would decrease because of larger sep

otential difference of 1 kV, its kinetic

al energy loss of the neutron in the collision

hickness 2 μm and refractive index 1.5 is introduced in the path of the upper beam. The location of the central maximum will-

an axis perpendicular to its plane and passing through a point on its rim will be-

erature of 6000K. Maximum intensity is en the peak intensity of emitted radiation would occur at a wavelength-

bsorbs 6 x 104 cal at the higher temperature. The amount of heat converted into work is-

elecl and magnetic fields are-

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ating photoemission. What is the ram of the work function of the tWI emitters?

solenoid is reversed in 0.25 see, the emf induced in th e coil is

(A) 48 volt

ould decrease because of larger separation between the centre of the planet and its surface. Which effect would dominate?

entral maximum will-