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. Radium Ra236 has a half-life of 1590 years. How much of the original amount of Ra236 would remain after 6360 years ?
A. 1/8
B. 1/4
C. 1/16
D. 1/2
2. The resistance of an ammeter is 13 ohms and its scale is graduated for a current upto 100 A. After an additional shunt has been connected to this ammeter it becomes possible to measure currents upto 750 A with this meter. The value of shunt resistance is
A. 20 ohms
B. 2 ohms
C. 0.2 ohms
D. 2k ohms
3. A wire of length L is drawn such that its diameter is reduced to half of its original diameter. If the initial resistance of the wire is 10 ohms, its new resistance would be
A. 40 ohms
B. 80 ohms
C. 120 ohms
D. 160 ohms
4. Two projectiles are fired from the same point with the same speed at angles of projection 60° and 30° respectively. Which one of the following is true?
A. Their maximum height will be same
B. Their range will be same
C. Their landing velocity will be same
D. Their time of flight will be same
5. A frog can be levitated in a magnetic field produced by a current in a vertical solenoid placed below the frog. This is possible because the body of the frog behaves as
A. Paramagnetic
B. Diamagnetic
C. Ferromagnetic
D. Antiferromagnetic
6. A child is swinging a swing. Minimum and maximum heights of swing from earth’s surface are 0.75 m and 2m respectively. The maximum velocity of this swing is?
A. 5 m/s
B. 10 m/s
C. 15 m/s
D. 20 m/s
7. The ratio of energy of emitted radiation of black body at 27°C and 927°C is
A. 1:256
B. 1:64
C. 1:16
D. 1:4
8. Consider a car moving along a straight horizontal road with a speed of 72 km/h. If the coefficient oi static friction between the tyres and the road is 0.5, the shortest distance in which the car can be stopped is g = 10 m/sec/sec
A. 20 m
B. 40 m
C. 30 m
D. 72 m
9. A beam of parallel rays is brought to focus by a plano-convex lens. A thin concave lens of the same focal length to joined to the first lens. The effect of this is
A. the focus shifts to infinity
B. the focal point shifts towards the lens by a small distance
C. the focal point shifts away from the lens by small distance
D. the focus remains undisturbed
10. A laser beam is used for carrying out surgery because it
A. ls highly monochromatic
B. ls highly coherent
C. ls highly directional
D. Can be sharply focused
11. 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
12. A proton and an alpha particle enter uniform magnetic field with the same velocity. The period of rotation of the alpha particle will be
A. the same as that of proton
B. three times that of proton
C. two times that of proton
D. four times that of proton
13. A neutron makes a head-on elastic collision with a stationary deuteron. The fractional energy loss of the neutron in the collision is
A. 16/81
B. 8/27
C. 8/9
D. 2/3
14. To use a transistor as an amplifier
A. Emitter-base junction is forward biased and collector-base junction is reversed biase
B. both junctions are reverse biased
C. both junctions are forward biased
D. It does not matter how the transistor is biased, it always works as an amplifier
15. A person swims in a river aiming to reach exactly opposite point on the bank of a river. His speed of swimming is 0.5 m/s at an angle 120° with the direction of flow of water. The speed of water in stream is ?
A. 1 m/s
B. 0.5 m/s
C. 0.43 m/s
D. 0.25 m/s
16. Two waves of lengths 50 cm and 51 cm produced 12 beats per second. The velocity of sound is
A. 360 rn/s
B. 340m/s
C. 331 m/s
D. 306 m/s
17. Density of wood is 0.5 kg /cc in the CGS system of units. The corresponding value in MKS units is
A. 5000
B. 0.5
C. 5
D. 500
18. A sphere of mass M and radius R is falling in a viscous fluid. The terminal velocity attained by the falling object will be proportional to
A. R x R
B. R
C. 1/R
D. 1/R/R
19. If an object is moving with a constant acceleration, the net force acting on that body ts
A. increasing
B. decreasing
C. constant
D. zero
20. A good floor lamp has a wlde heavy base to increase its stability through
A. increasing contact area
B. lowering the center of gravity
C. raising the center of gravity
D. None of the above
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