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| VALUABLE PHYSICS MCQ |
1. In a system of units , the units of length, mass and time are 10 cm, 10g and 0.1 s respectively. The unit
of force will be equivalent to :
a) 0.1 N b) 1N c) 10 N d) 100 N
2. Two balls of same mass are projected with the same speed: one vertically upwards and the other at
angle of 60* with the vertical. The ration of their potential energy at the highest point is :
a) 3 : 2 b) 2 : 1 c) 4 : 1 d) 4 : 3
3. A solid sphere of mass 500g and radius 10 cm rolls down an inclined plane without slipping and
without loss of energy . The height of the top of the inclined plane above the bottom is 0.7m . Given that g = 10 m/s2 , the linear speed of the sphere on reaching the bottom will be :
a) 1.6 m /s b) 3.2 m/s c) 6.4 m/ s d) none of these
4. A body B1 is projected upwards with velocity v1 . Another body B2 of same mass is projected at an
angle 45* . Both reach the same height , what is the ratio of their initial kinetic energies ?
a) 1 / 4 b) 1 / 3 c) 1 / 2 d) 1
5. A mass of 1kg is suspended from a spring . Its time period of oscillation on the earth is T . What will
be its time period at the centre of the earth ?
a) zero b) T c) 2T d) Infinite
6. The length of an elastic string is x when the tension is 5 N . Its length is y when the tension is 7 N .
what will be its length , when the tension is 9 N ?
a) 2y + x b) 2y -- x c) 7x -- 5y d) 7x + 5y
7. One soap bubble P has radius r , another Q has radius 2r . The two come into contact to form a
common interface wall . The radius of curvature of this wall will be :
a) 2r concave towards P b) 2r concave towards Q c) 3r concave towards P
d) 3r concave towards Q
8. Two gases A and B having the same temperature T, same pressure P and same volume V are mixed .
If the temperature of the mixture remains unchanged and the volume occupied by it is V , then the
pressure of the mixture will be :
a) P / 2 b) P c) 2P d) 4P
9. A wave of length 2m is superimposed on its reflected wave to form a stationary wave . A node is
located at x = 3 m , the next node will be located at x equals to :
a) 3.25 m b) 3.50 m c) 3.75 m d) 4 m
10. A source of sound emits 200πW power which is uniformly distributed over a sphere of 10 m radius .
What is the loudness of sound on the surface of a sphere ?
a) 200 dB b) 200 π dB c) 120 dB d) 120 π dB
11. A convex lens of focal length 20 cm is placed co-axially with a concave lens of focal length 5 cm.
The parallel beam incident on convex lens leaves the concave lens as parallel beam. What is the
separation between that lenses ?
a) 20 cm b) 15 cm c) 10 cm d) 5 cm
12. The angle between the incident ray and the reflected ray from a plane mirror is 60* . Through what
angle is the reflected ray deviated with respect to the incident ray ?
a) 150* b) 120* c) 90* d) 60*
13.While reading the book a man keeps the page at a distance of 2.5cm from his eye. He wants to read
the book by holding the page at 25 cm. What is the nature of spectacles one should advice him to use
to completely cure his eye sight ?
a) convex lens of focal length 25 cm b) concave lens of focal length 25 cm
c) convex lens of focal length 2.5 cm d)concave lens of focal length 2.5 cm
14. A ray of light is incident on a glass plate at 60* . The reflected and refracted rays are found to be
mutually perpendicular. The refractive index of the glass is :
a) 2 b) 1.73 c) 1.50 d) 1.15
15. In the interference pattern produced by two identical slits, the intensity of central maximum is I .
What will be the intensity of light at the same spot , if one of the slits is closed ?
a) I b) I / 2 c) I / 4 d) I / 8
16.A heater boils 1kg of water in time t1 and another heater boils the same water in time t2 . If both are
connected in series the combination will boil the same water in time :
a) t1t2 / t1 -- t 2 b) t1t2 / t1 + t2 c) t1 + t2 d) 2(t1+t2 )
17. What should be the rate of variation of current in self inductance 1H to generate induced emf equal to
1V ?
a) Less than 1A / s b) 1A / s c) 2A / s d) more than 2A /s
18. A choke coil and a capacitor are connected in series and the current through the combination is
maximum for AC of frquency f . If they are connected in parallel , at what frequency the current
through the combination is minmum ?
a) f b) f / 2 c) 2f d) None of the above
19. The energy difference between the first two levels of hydrogen atom is 10.2 eV . For another element of atomic number 10 and mass number 20 will be :
a) 1020 eV b) 2040 eV c) 0.51 eV d) 0.102 eV
20. The potential difference applied to an X -rays tube is increased. As a result in the emitted radiation ,
the :
a) intensity increases b) minimum wavelength increase c) intensity decreases d) minimum
wavelength decreases
21. The phenomenon of pair production is :
a) the production of an electron and positron from gamma rays
b) ejection of an electron from a metal surface when exposed to ultraviolet light
c) ejection of an electron from a nucleus
d) ionisation of a neutral atom
22. A certain radioactive substance has ahalf life of 5 years. Thus for a nucleus in a sample of the element
,probability of decay in 10 years is :
a) 50% b) 75% c) 60 % d) 100 %
23. Why do the conduction electrons have greater mobility than that of holes ?
a) They are lighter b) They carry -ve charge c) Need less energy for movement
d) Experience less collisions
24. In a full wave rectifier circuit operating from 5o Hz mains frequency , the fundamental frequency in
the ripple would be :
a) 25 Hz b) 50 Hz c) 70.7 Hz d) 100 Hz
25. One mole of monoatomic gas and one mole of a diatomic gas are mixed together . What is the molar
specific heat at constant volume for the mixture ?
a) 3/2 R b) 2R c) 5/2 R d) 3R
26. Bernoulli's equation is a consequence of conservation of :
a) energy b) linear momentum c) angular momentum d) mass
27. 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
28. 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 were 10 ohm , its new resistance would be :
a) 40 ohm b) 80 ohm c) 120ohm d) 160ohm
29. A proton is about 1840 times heavier than an electron .When it is accelerated by a potential difference
of 1 kV , its kinetic energy will be :
a) 1840 keV b) 1 / 1840 keV c) 1 keV d) 920 keV
30. An electric dipole placed in a non uniform 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
31. In an ideal parallel LC circuit the capacitor is charged by connecting it to a DC source which is then
disconnected . The current in the circuit :
a) becomes zero instantaneously b) grows montonically c) decays montonically
d) oscillates instantaneously
32. To a Germanium sample traces of Gallium are added as an impurity. The resultant sample would
behave like :
a) a conductor b) a p-type semiconductor c) an n- type semiconductor d) an insulator
33. A radioactive substance decays 1/16th of its initial activity in 40 days .The half life of the radioactive
substance expressed in days is :
a) 2.5 b) 5 c) 10 d) 20
34. 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 / 9 c) 8 /27 d) 2/3
35. 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
36. Parsec is the unit of :
a) time b) distance c) frquency d) angular acceleration
37. A block of mass 10kg is moving in x direction with a constant speed of 10 m/s . It is subjected to a
retarding force F = 0.1 x J/m during its travel from x = 20 m to x = 30 m. Its final kinetic energy will
be:
a) 475 J b) 450J c) 275 J d) 250 J
38. Which of the following is an amorphous solid ?
a) Glass b) Diamond c) Salt d) Sugar
39. In case of linearly polarised light , the magnitude of the electric field vector :
a) does not change with time b) varies periodically with time c) increases and decreases linearly
with time d) is parallel to the direction of propagation
40. Which of the following logic gates is an universal gate ?
a) OR b) NOT c) AND d) NAND
41. The ground state enrgy of hydrogen atom is -- 13.6 eV . What is the potential energy of the electron
in these state ?
a) Zero b) -- 27.2 eV c) 1 eV d) 2 eV
42. When exposed to sunlight thin films of oil on water often exhibit brilliant colours due to the phenom-
enon of :
a) interference b) diffraction c) dispersion d) polarisation
43. A person is standing in an elevator. In which situation he finds his weight less ?
a) when the elevator moves upward with constant acceleration
b) when the elevator moves downward with constant acceleration
c) when the elevator moves upward with uniform velocity
d) when the elevator moves downward with uniform velocity
44. The Magnetic Resonance Imaging (MRI) is based on the phenomenon of :
a) nuclear magnetic resonance b) electron spin resonance c) electron paramagnetic resonance
d) diamagnetism of human tissues
45. An organ pipe closed at one end has fundamental frequency of 1500 Hz . The maximum number of
overtones generated by this pipe which a normal person can hear is ?
a) 4 b) 13 c) 6 d) 9
BEST OF LUCK
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