1 An electron moving in an electromagnetic field moves in a
(a) In a straight path
(b) Along the same plane in the direction of its propagation
(c) Opposite to the original direction of propagation
(d) In a sine wave
Ans. (b)
2. The total work done on the particle is equal to the change in its kinetic energy
(a) Always
(b) Only if the forces acting on the body are conservative.
(c) Only if the forces acting on the body are gravitational.
(d) Only if the forces acting on the body are elastic.
Ans. (a)
3. The following unit measure energy:
(a) Kilo-watt hour.
(b) Volt*volt/sec*ohm.
(c) Pascal*foot*foot
(d) (Coulomb*coulomb)*farad
Ans. (a)
4. Astronauts in stable orbits around the earth are in a state of weightlessness because
(a) There is no gravitational force acting on them.
(b) The satellite and the air inside it have an acceleration equal to that of gravitational acceleration there.
(c) The gravitational force of the earth and the sun balance giving null resultant.
(d) There is no atmosphere at the height at which the satellites move.
Ans. (b)
5. An organ pipe, open at both ends and another organ pipe closed at one end, will resonate with each other, if their lengths are in the ratio of
(a) 1:1
(b) 1:4
(c) 2:1
(d) 1:2
Ans. (c)
6. During an isothermal expansion of an ideal gas
(a) Its internal energy increases.
(b) Its internal energy decreases.
(c) Its internal energy does not change.
(d) The work done by the gas is not equal to the quantity of heat absorbed by it.
Ans. (c)
7. A parallel plate capaciator is charged and the charging battery is then disconnected. If the plates of the capacitor are moved further apart by means of insulating handles
(a) The charge on the capacitor increases.
(b) The voltage across the plates increases.
(c) The capacitance increases.
(d) The electrostatic energy stored in the capacitor decreases.
Ans. (b)
8. Two equal negative charges q are fixed at point (0,a) and (0,-a) on the y-axis.A positive charge Q is released from rest at the point (2a,0) on the x-axis. The charge Q will
(a) Execute simple harmonic motion about the origin
(b) Move to the origin and remain at rest
(c) Move to infinity
(d) Execute oscillatory but not simple harmonic motion
Ans. (d)
9. A square conducting loop of length Lon a side carries a current I.
The magnetic field at the centre of the loop is
(a) Independant of L
(b) Proportional to L*L
(c) Inversely proportoinal to L
(d) Directly proportional to L
Ans. (c)
10. The focal length of a convex lens when placed in air and then in water will
(a) Increase in water with respect to air
(b) Increase in air with respect to water
(c) Decrease in water with respect to. air
(d) Remain the same
Ans. (a)
11. The maximum kinectic energy of the photoelectron emitted from the surface is dependant on
(a) The intensity of incident radiation
(b) The potential of the collector electrode
(c) The frequency of incident radiation
(d) The angle of incidence of radiation of the surface
Ans. (c)
12. An electron orbiting in a circular orbit around the nucleus of the atom
(a) Has a magnetic dipole moment
(b) Exerts an electric force on the nucleus equal to that on it by the nucleus
(c) Does not produce a magnetic induction at the nucleus
(d) All of the above
Ans. (d)
13. The X-rays beam coming from an X-ray tube will be:
(a) Monochromatic
(b) Having all wavelengths smaller than a certain minimum wavelength
(c) Having all wavelengths larger than a certain minimum wavelength
(d) Having all wavelengths lying between a minimum and a maximum wavelength
Ans. (c)
14. The mass number of a nucleus is
(a) Always less than its atomic number
(b) Always more than its atomic number
(c) Always equal to its atomic number
(d) Sometimes more and sometimes equal to its atomic number
Ans. (d)
15. Two successive elements belonging to the first transition series have the same number of electrons partially filling orbitals. They are
(a) V and Cr
(b) Ti and V
(c) Mn and Cr
(d) Fe and Co
Ans. (c)
16. When n+l has the same value for two or more orbitals,the new electron enters the orbital where
(a) n is maximum
(b) n is minimum
(c) l is maximum
(d) l is minimum
Ans. (b)
17. A balloon filled with ethylene is pricked with a sharp pointed needle and quickly placed in a tank full of hydrogen at the same pressure. After a while the balloon would have
(a) Shrunk
(b) Enlarged
(c) Completely collapsed
(d) Remain unchanged in size
Ans. (b)
18. Which of the following statements is not true?
(a) The ratio of the mean speed to the rms speed is independant of temperature
(b) The square of the mean speed of the molecules is equal to the mean squared speed at a certain temperature
(c) Mean kinetic energy of the gas molecules at any given temperature is independant of the mean speed
(d) None
Ans. (b)
