Lecturer of Physics PPSC Past Paper

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

expression:

(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

16) In an Adiabatic process:

(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= 4Ω, Xc = 3 and XL=6, the impedence of the circuit is:

(a) 5 Ω  (b) 7 Ω  (c) 13 Ω    (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 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