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. A bomb of mass 3.0 kg explodes in air into two pieces of masses 2.0 kg and 1.0 kg. The smaller mass goes at a speed of 80 m/s. The total energy imparted to the two fragments is
A. 1.07 kJ
B. 2.14 kJ
C. 2.4 kJ
D. 4.8 kJ
2. An endoscope is employed by a physician to view the intemal parts of a body organ. It is based on the principle of
A. Refraction
B. Reflection
C. Total internal reflection
D. Dispersion
3. 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
4. ln a nuclear reactor
A. the thick concrete shield is used to slow down the speed of neutrons
B. heavy water or graphite is used to moderate the activity of the reactor
C. the chain reaction is controlled by rods of uranium whose going in reduces the rate
D. out of U238 and U235, the natural uranium has less than 1 % of dU 235
5. A spring of of force constant it is cut into three equal pieces. If these three pieces are connected in parallel, the force constant of the combination will be
A. 3k
B. 9k
C. k
D. k/3
6. An astronaut is accelerated in his spacecraft from rest to 800mi./hr. in 60 sec. He was subjected to an acceleration of
A. 4800 ft/sec/sec
B. 1200 mi./hr/hr
C. 4800 mi./hr/hr
D. 48000 mi./hr/hr
7. Four perfect poiarising stacked so that the axis of each is turned 30° clockwise to the preceding plate, the last plate therefore being crossed with the first. A beam of unpolarised light of intensity I passes through the stack perpendicularly. The transmitted beam has intensity
A. 27 x I/128
B. 81 x I/256
C. 1 x I/8
D. 27 x I/64
8. 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
9. Two blocks of equal mass 3 kg, connected by a light string, are placed on a horizontal surface which is not frictionless. If a force of 20 N is applied in the horizontal direction on a block, the acceleration of each block is 0.5 m/s/s. Assuming that the frictional forces on the two blocks are equal, the tension in the string will be
A. 60 N
B. 40 N
C. 20 N
D. 0 N
10. In a carbon monoxide molecule, the carbon and the oxygen atoms are separated by a distance 1.12E-10 m. The distance of the centre of mass from the carbon atom is
A. 0.64E-10 m
B. 0.56E-10 m
C. 0.51E-10 m
D. 0.48E-10 m
11. A beam of electrons passes undeflected through mutually perpendicular electric and magnetic fields. If the electric field is switched off and the same magnetic field is maintained. the electrons move
A. in an elliptical orbit
B. in a circular orbit
C. along a parabolic path
D. along a straight line
12. A parallel plate capacitor is made by stacking n equally spaced plates connected alternatively. If the capacitance between any two adjacent plates is C then the resultant capacitance is
A. n-1C
B. n+1C
C. C
D. nC
13. A nucleus of mass number A, originally at rest, emits an alpha - particles with speed v. The daughter nucleus recoils with a speed
A. 2v/A + 4
B. 4v/A + 4
C. 4v/A - 4
D. 2v/A - 4
14. A spherical ball contracts in volume by 0.01% when subjected to a normal uniform pressure of 100 atmospheres. The built modulus of its material in dyne/cm square is
A. 2.0E11
B. 1E12
C. 100E12
D. 10E12
15. 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
16. Radioactive nuclei that are injected into a patient collect at certain sites within its body, undergoing radioactive decay and emitting electromagnetic radiation. These radiations can then the recorded by detector. This procedure provides an important diagnostic tool called
A. Gamma camera
B. CAT scan
C. Radiotracer technique
D. Gamma ray spectroscopy
17. 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
18. A common emitter amplifier has a voltage gain of 50, an input impedance of 100 ohms and an output impedance of 200 ohms. The power gain of the amplfier ia
A. 500
B. 1000
C. 1250
D. 100
19. 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 of electrons with atoms in the target
20. 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
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