# PPSC Lecturer Physics MCQs Sample Past Papers

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 dΦ/dt  (c) e = – L di/dt  (d) None of these
30)  Inductive reactance of an inductor is:
(a) XL= ω2L  (b) XL= ω/L  (c) e = -L di/dt  (d) None of these
31) The resonant frequency of an LC-Circuit is:
(a)  f = 2Π LC  (b)  f = 1 / 2Π√ 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 α-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) 0.2π(b)  π(c) 2π(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
(d) None of these
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
(d) None of these
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 i
ncrease 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

First 25 Questions Visit here