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

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= 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

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