# PPSC Lecturer of Physics Past Paper

(1) If A= 6i-8j, then 4A has the magnitude:

(a) 40 (b) 10 (c) 20 (d) None of these

2) Let A= 2i+6j-3k and B= 4i+2j+k then A.B equals:

(a) 8i+12j-3k (b) 17 (c) 23 (d) None of these

3) If V is an operator, then V.V means:

(a) Gradient of a Scalar field

(b) Curl of a vector field
(c) Divergence of a Vector field

(d) None of these

4) The volume of a parallelepiped bounded by Vectors A,B and C can be obtained from the:

(a) ( A x B ).C

(b) (A.B)x C

(c) ( A x B ) x C

(d) None of these

5) A force acting on a particle is conservative if:

(a) It obeys Newton’s third law

(b) It obeys Newton’s second law
(c) It works equals the change in Kinetic energy

(d) None of these

6) A torque applied to a rigid object always tends to produce:

(a) A rotational acceleration

(b) A linear acceleration
c) Precision

(d) None of these

7) When the velocity of a body is constant, its acceleration is:

(a) Maximum (b) Zero (c) Infinity (d) None of these

8) In the absence of external torque the total angular momentum is:

(a) Constant (b) Zero (c) infinity (d) None of these

9) The rate of change of Momentum of the particle is:

(a) Energy (b) Force (c) Impulse (d) None of these

10) The intensity of a wave is proportional to the square of:

(a) Amplitude (b) Time (c) Intensity (d) None of these

11) The colours in soap bubbles, oil slick etc. in a thin film is due to:

(a) Diffraction

(b) Polaristaion

(c) Interference

(d) None of these

12) For higher resolution, in a diffraction grating, one needs to have:

(a) Large number of ruling

(b) Small number of ruling
(c) No rulings at all

(d) None of these

13) To produce interference, the sources must be:

(a) Intense (b) Incoherent (c) Coherent (d) None of these

14) Interference fringes are of:

(a) Unequal width (b) Equal width (c) Variable width (d) None of these

15) A Carnot Cycle is:

(a) a rectangle on a P-V graph

(b) bounded by two isotherms and two adiabatics
(c) any four sided process on a P-V graph

(d) None of these

(a) The temperature of the system remains constant

(b) The temperature of the system must change

(c) The internal energy of the system remains constant

(d) None of these

17) A Carnot Cycle heat engine operates between 227°C and 127° C. Its efficiency is:

(a) 44% (b) 20% (c) 79% (d) None of these

18) Metals pipe carrying water some times bursts in winter because:

(a) Water expands

(b) Ice expands when melts

(c) Metal contracts more than water

(d) None of these

19) A Fahrenheit thermometer and Celsius thermometer shows the same reading at:

(a) 200° (b) -40° (c) 100° (d) None of these

20) Constructive and destructive superposition of waves is observed in:

(a) Polarisation

(b) Interference

(c) Diffraction

(d) None of these

21) A Watt – sec is a unit of:

(a) Force (b) Energy (c) Power (d) None of these

22) The direction of any magnetic induction effect is such as to oppose the cause of the effect. This is:

(a) Coulumb’s Law

(b) Ampere’s Law

(c) Lenz’s Law

(d) None of these

23) A magnetic field cannot:

(a) accelerate a charge

(b) Exert a force on a charge
(c) change the kinetic energy of a charge

(d) None of these

24) The inverse of resistivity is called Conductivity. Its unit is:

(a) Ohm-1

(b) ohm-metre

(c) (ohm-meter)-1

(d) None of these

25 An LRC Circuit has R= 4O, Xc = 3 and XL=6, the impedence of the circuit is:

(a) 5 O (b) 7 O (c) 13 O (d) None of these

26) A “step-down” transformer is used to:

(a) increase the power

(b) decrease the voltage

(c) Increase the voltage

(d) None of these

27) Electrical potential is the potential energy per unit:

(a) Charge (b) Voltage (c) Force (d) None of these

28) The force on a charge moving with the velocity in a magnetic field B is given by:

(a) F = (q/v x B)

(b) F = ( qv x B )

(c) F = (qv + B)

(d) None of these

29) A changing current “i” in any circuit induces an emf “e” in that circuit, which is equal to:

(a) e = di/dt (b) E = i dF/dt (c) e = – L di/dt (d) None of these

30) Inductive reactance of an inductor is:

(a) XL= ?2L (b) XL= ?/L (c) e = -L di/dt (d) None of these

31) The resonant frequency of an LC-Circuit is:

(a) f = 2? LC (b) f = 1 / 2?√ LC (c) f = 1/ 2LC (d) None of these

32) The deliberate addition of an impurity element in a semi-conductor is called:

(a) doping (b) annealing (c) mixing (d) None of these

33) The conversion of AC into DC is called:

(a) amplification

(b) rectification

(c) modulation

(d) None of these

34) The Laser light is:

(a) monochromatic

(b) coloured

(c) chromatic

(d) None of these

35) The Laser light may be obtained from:

(a) quartz crystal

(b) NaCl crystal

(c) ruby crystal

(d) None of these

36) The emission of photoelectrons in photoelectric effect is dependent on:

(a) threshold frequency

(b) intensity of light

(c) Nature of metal

(d) None of these

37) Which one of the following is NOT needed in Nuclear Fission reactor:

(a) fuel (b) accelerator (c) moderator (d) None of these

38) The half life of a radioactive isotope is 140 days. How many days would it take to loose 3/4 of its initial activities:

(a) 105 days (b) 280 days (c) 35 days (d) None of these

39) Most of the energy produced in Sun is due to:

(a) Nuclear fusion

(b) Chemical reaction

(c) Nuclear Fission

(d) None of these

40) A U-235 nucleus will split when it captures:

(a) an a-particle (b) e.m. radiation (c) neutron (d) None of these

41) Two particles each of mass 5.0kg are mounted 4.0m apart on a mass-less light rod which is capable of rotation about its center? The moment of inertia is:

(a) 1.25 kgm2(b) 20 kgm2(c) 40 kgm2(d) None of these

42) The time period of mass of 1kg attached to a spring of spring constant of 100N/m is:

(a) 0.2p(b) p(c) 2p(d) None of these

43) A 14cm inner diameter water main furnishes water (through intermediate pipes) to a 1.00cm inner diameter faucet pipe. If the average speed in the faucet pipe is 3.0 cm/s, what will be the average speed it causes in the water main?

(a) 0.015 cm/s (b) 0.15 m/s (c) 0.5 m/s (d) None of these

44) What is the tension T in the rope if a 10N weight is being pulled upward by it with a constant velocity of 2m/s?

(a) 12N (b) 8N (c) 5N (d) None of these

45) The ratio of linear Stress/Linear Strain is called:

(a) Young’s Modulus

(b) Bulk Modulus

(c) Deformation

(d) None of these

46) A body is moving with constant speed in a circle, its velocity vector:

(a) Remains constant

(b) Changes its magnitude

(c) Changes its direction

47) When a constant torque is acting on a rotating system, which of the following is constant?

(a) Angular velocity

(b) Angular acceleration

(c) Angular momentum

48) A geo-stationary satellite revolves around the earth from:

(a) East to west

(b) West to east

(c) North to south

(d) None of these

49) According to Einstein, with the great increase in the speed of a body, the relativistic is:

(a) Length remains constant

(b) Time decreases
(c) Mass increases

(d) None of these

50) A body is moving northward and the force applied is eastward, the acceleration produced is:

(a) Northward

(b) At 45oEast of North

(c) Eastward

(d) None of these