FPSC lecturer physics bs-17

1.Which of the following statements is false for a particle moving in a circle with a constant angular speed?

(A) The velocity vector is tangent to the circle.

(B) The acceleration vector is tangent to the circle.

(C) The acceleration vector points to the centre of the circle.

(D) The velocity and acceleration vectors are perpendicular to each other.

2.A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle, the motion of the particle takes place in a plane. It follows that

(A) its velocity is constant

(B) its acceleration is constant

(C) its kinetic energy is constant

(D) it moves in a straight line

3.The dispersion of light in a medium implies that

(a) Lights of different wavelengths travell with different speeds in the medium.

(b) Lights of different frequencies travell with different speeds in the medium.

(c) The refractive index of medium is different for different wavelengths of light.

(d) All of the above

4.During the X-Ray emission , if the voltage is increased

(a) minimum wavelength decreases

(b) minimum wavelength increases

(c) intensity decreases

(d) intensity increases

5.Force exerted on a body can change its

a. kinetic energy
b. direction of motion
c. speed and momentum
d. All above

6.Kirchoff’s first law of electric circuits is based on the law of conservation of

a) only on mass
(b) only on charge
(c) on charge as well as on energy
(d) on charge as well as on mass

7.If a particle moving in a magnetic field , increases its velocity, then its radius of magnetic field energy will

(a) remain constant
(b) decrease
(c) increase
(d) either b or c

8.A particle executes SHM with frequency f. The frequency with which its Kinetic energy oscillates is

(a) f/2
(b) f
(c) 2f
(d) 4f

9.An atom is paramagnetic if it has

(a) an electric dipole moment
(b) no magnetic moment
(c) a magnetic moment
(d) no electric dipole moment

10.Magnetic moment of a diamegnetic atim is

(a) 0
(b) infinity
(c) negative
(d) positive

11.The line on the earth’s surface joining the points where the field is horizontal is called

(a) magnetic maredian
(b) magnetic axis
(c) isogonic line
(d) magnetic equator

12.The principle used in the transmission of signal through an optical fibre is

(a) total internal reflection
(b) reflection
(c) refraction
(d) dispersion

13.Which of the following is a Vector?

i> Energy
ii> Power
iii> Force
iv> Mass

14. Which of the following is a vector?

i> Time
ii> Work
iii> Heat
iv> Momentum

15.Which of the following is a scalar?

i> Elementary area
ii> Kinetic energy
iii> Weight of a body
iv> Wind velocity

16. Which of the following is a scalar?

i> Electric field
ii> Magnetic Moment
iii> Acceleration
iv> Electrostatic Potential

17. Moment of inertia is:

i> A scalar
ii> A vector
iii> A tensor
iv> Same as mass

18. Lorentz force is the sum of:

a) Gravitational and centripetal force
c) Magnetic and nuclear force
d) Electrical and nuclear force

19. The areas under the hysteresis loop is proportional to

a) Magnetic energy density
b) Thermal energy per unit volume

20. The frequency of A.C is measured using:

a) Multimeter b) avometer c) TACHOMETER d) speedometer

21. Del. E = rho/epsilon not is called

a) GAUSS’S LAW b) faraday’s law c) ampere’s law d) biot savart’s law

22. Semiconductor materials have _____ bonds.

a) Ionic b) COVALENT c) mutual d) metallic

23. The depletion region of a pn junction is formed:

a) During the manufacturing process
c) Under reverse bias

24. The current amplification factor DC is given by:

A) IC/IE b) Ic/Ib c)Ib/Ie d) Ib/Ic

25.In amplitude modulation

a) Carrier frequency is changed
c) Three sidebands are produced
d) Fidelity is improved

26. Demodulation

a) Is performed at the transmitting station
b) Removes side bands
c) Rectifies modulation signal

28.Which of the following expression does not represent the force acting on the body of mass m

a. GMem/(Re)2
b. ma
c. µN
d. 6?prv

29. Heat cannot by itself flow from a body at lower temperature to a body at higher temperature” is a statement of consequence of

(A) second law of thermodynamics
(B) conservation of momentum
(C) conservation of mass
(D) first law of thermodynamics.

30. Which of the following parameters does not characterize the thermodynamic state of matter?

(A) temperature
(B) pressure
(C) work
(D) volume

31. Which of the following statements is correct for any thermodynamic system?

(A) The internal energy changes in all processes.
(B) Internal energy and entropy are state functions.
(C) The change in entropy can never be zero.
(D) The work done in an adiabatic process is always zero.

32. when a solid metalic sphere is heated.the largest percentage increase occurs in its

b. Surface area
c. Volume
d. density

33. A metallic sphere has a cavity of diameter D at its center.If the sphere is heated,the diameter of the . cavity will

a. Decrease
b. Increase
c. Remain unchanged
d. none of the above

35.what is true for a free expansion process

a. dW=0
b. dQ=0
c. dU=0
d. all the these

37. if dU=-dW for a process,the process is

a. Adiabatic
b. Isothermal
c. Isobaric
d. None of the abobe

38. The amount of energy radiated by a body depends on

a.The nature of the surface
b. The area of the surface
c. Temperature of the surface
d. all the these
e. none of these

39. The wavelenght of the radiation emitted by the body depends on

a.The nature of the surface
b. The area of the surface
c. Temperature of the surface
d. all the above

40. An ideal black body is thrown in the furnace.It is observed that

a. Intially it is the darkest body and at later times the brightest
b. it is the darkest body all the times
c. It cannot be distinguish at all the times
d. Intially it is the darkest body and at later times It cannot be distinguish

42.One end of a metal rod is kept in a furnace.In steady state,the temperature of the rod

a. Increase
b decrease
c. remains constant
d. is non uniform

43. what is true for black body

a refract radiation
b emit radiation and absorb radiation
c. just absorb radiation
d. just emit radiation

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