A fresh set of 20 random questions is generated every time you open this page and every time you refresh it.For each of the following multiple choice questions, choose the most appropriate answer :
1. When exposed to sunlight, thin films of oil on water often exhibit brilliant colours due to the phenomenon of
A. Interference
B. polarization
C. diffraction
D. dispersion
2. An earthquake generates both transverse S and longitudinal P sound waves in the earth . The speed of S waves is about 4.5 km/s and that of P waves is about 8.0 km/s. A seismograph records P and S waves from an earthquake . The first P wave arrives 4.0 min before the first S wave. The epicenter oi the earthquake is located at a distance of about
A. 25 km
B. 250 km
C. 2500 km
D. 500km
3. The wavelength of light of a particular wavelength received from a galaxy is measured one earth and is found to be 5% more that its wavelength. It follows that the galaxy is
A. going away from the earth with a speed 1.5E7/ms
B. approaching the earth with a speed 1.5E7/ms
C. going away from the earth with a speed 3E7/ms
D. approaching the earth with a speed 3E7/ms
4. 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
5. A soap bubble is vacuum has a radius of 3 cm and another soap bubble in vacuum has a radius of 4cm. If the two bubbles coalesce under isothermal conditionals the radius of the new bubble will be
A. 7 cm
B. 5 cm
C. 4.5 cm
D. 2.3 cm
6. Bermoulli's equation is a consequence of conservation of
A. Energy
B. Linear momentum
C. Angular momentum
D. Mass
7. Which of the statements below is courect ?
A. The angle of bank for a road is obtained from a consideration of the centripetal force required
B. There is no tendency for the vehicle to skid if a road is banked for the speed at which the vehicle is moving
C. C. The resultant force action on the vehicle will be that which maintains it in the circular path
D. All of the above statements are correct
8. Two parallel wires in free space are 10 cm apart and each carries a current of 10 A in the same direction. The force one wire exerts on the other per metre of length is
A. 2E-7 N. repulsive
B. 2E-7 N. attractive
C. 2E-4 N, repulsive
D. 42E-4 N, attractive
9. The decrease in the potential energy of a ball of mass 20 kg which falls from a height of 50 cm is
A. 98 J
B. 968 J
C. 1980 J
D. None of these
10. In case of linearly polarized light, the magnitude of the electric field vector
A. increases and decreases linearly with time
B. is parallel to the direction of propagation
C. does not change with time
D. varies periodically with time
11. lf the mass of a moving projectile is tripled and its velocity is doubled, the kinetic energy will be multiplied by
A. 8
B. 6
C. 2
D. 12
12. When light is reflected from a surface, lt can be either regular reflection or diffuse reflection. The essential difference between regularly and diffusely reflecting surfaces is that
A. regularly reflecting surfaces are smoother than diffusely reflecting surfaces
B. light can not be reflected from a diffusely reflecting surface
C. the regularly reflecting surface is coarser than the diffusely reflecting surface
D. all of the above are essential differences between regularly and diffusely reflecting surfaces
13. When a beta-particle is emitted from a nucleus, the neutron-proton ratio
A. is increased
B. is decreased
C. remains the same
D. first decreases then increases
14. A solid cylinder of mass 20 kg is turned by 50 W motor against a friction band. After 4 minutes, the temperature rises from 20°C to 30°C. The specific heat capacity of the material oi the cylinder is
A. 600 J/kg
B. 200 J/kg
C. 150 J/kg
D. 10 J/kg
15. Which one of the following is not a "Black-body” ?
A. A highly polished black car
B. Uniform temperature enclosure
C. Platinum black
D. The sun
16. A radio or T.V. set which uses valves does not start operating immediately when it switched on, whereas the set only containing transistors operates immediately. The reason for this is that
A. Current does not have so far to go in a transistor set
B. Filament of the value takes time to heat up
C. Valve set works at a higher voltage
D. Transistor set has a lower resistance
17. The volume of a confined gas varies inversely with the absolute pressure provided that the temperature remains unchanged. This statement is known as
A. Dalton's law
B. Bemoulli's law
C. Avagadro`s law
D. Boyle's law
18. A concave lens of focal length 20 cm placed in contact with a plane mirror acts as a
A. concave mirror of focal length 10 cm
B. concave mirror of focal length 60 cm
C. concave mirror of focal length 40 cm
D. convex mirror of focal length 10 cm
19. Which statement below is true ?
A. Radiant energ; is propagated as a wave motion
B. Positions have the same mass as an electron
C. When a nucleus emits a beta particle, its mass number is unchanged
D. All of ihe above
20. A six pole generator with fixed field excitation develeps an emf of l00V, when operating at 1500 rpm. At what speed must it rotate to develop 120V?
A. 1200 rpm
B. 1800 rpm
C. 1500 mm
D. 400 mm
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