Model paper For AIR DD Engineering assistants

AIR ENGINEERING ASSISTANTS written test of two hours duration
one paper having 175 objective type questions based on the syllabus of three years Diploma/ B.Sc (Physics) 25 objective type questions on General Knowledge and Current Affairs. Each
question will carry two marks. Negative marking will be resorted for wrong answer. One mark will be deducted for each wrong answer.

Questions on electrostatic ,Wires carrying charge,induced field and potential.Intensity of charged particles ,induced field in circular coil , electromagnet and electromagnetic field ,dipole moment Units like coulomb,unit of force,gauss,potential energy,electrostatics Physics knowledge quizz free

1. A particle is moving uniformly with an angular velocity ω on the circumference of a circle of radius r. The linear velocity will be given by
(a) r ω
(c) r/ ω
(b)2πr ω
(d) ω/r

Ans:a

2. Line spectrum is obtained from the?
(a) Sun
(b) Filament of the bulb
(c) Mercury lamp
(d) Burning coal

Ans:c

3. A moving charge produces:
(a) neither electric field nor magnetic field
(b) electro-static field only
(c) magnetic field only
(d) both magnetic and electro-static fields

Ans:c

4. α, β and γrays emitted from a radioactive source are passed through a 0.5 cm. thick aluminum sheet. The out going radiations will consist of:
(a) α, β and γray
(b) β and γray
(c) γray
(d) αrayrays
Ans:b

5. Light year is a unit of
(a) time
(b) distance
(c) velocity
(d) acceleration

Ans:b
6. It is easier to draw up wooden block along an inclined plane than bang it up vertically principally because:
(a) the friction is reduced
(b) only a part of the weight has to be overcome
(c) the mass becomes smaller
(d) g becomes smaller
Ans:b

7. If a piece of ice floating on the surface of water in a beaker melts completely, the level of water
(a) rises
(b) remains the same
(c) falls
(d) initially rises and then falls
Ans:b

8. A Kelvin thermometer and a Fahrenheit thermometer used to record temperature of melting metal, read the same. What will a celcius thermometer read at that temperature?
(a) 301.25°
(b) 273°
(c) 457°
(d) 760°
Ans:a

9. A hydrogen-filled balloon expands as it rises and may even burst after rising very high in the atmosphere. This happens because:
(a) the temperature increases with height
(b) the temperature decreases with height
(c) the atmospheric pressure increases with height
(d) the atmospheric pressure decreases with height

Ans:d

10. if two substances of equal volumes but of different densities are dropped from the same height simultaneously, then
(a) the body of lower density will reach the earth earlier
(b) both the bodies will reach the earth simultaneously
(c) The body of higher density will reach earlier
(d) It depends upon the place
Ans:b

11. When the bob of a pendulum is at the mean position (minimum displacement) of its motion, its total energy is:
(a) all potential
(b) zero
(c) all kinetic
(d) partly kinetic partly potential
Ans:c

12. A red and a green pencil are taken in a room illuminated with green light. In the room:
(a) both pencils will appear dark
(b) pencils will appear as red and green respectively
(c) red pencil.will appear dark and green pencil as green
(d) red pencil will appear red and green pencil dark

Ans:c

13. The consumption of electrical energy in the household is measured in terms of:
(a) Kilowatt hour
(b) Kilowatts
(c) Joules
(d) Kilo Joules

Ans:a

14. A magnet is placed in earth’s magnetic field with north pole of the magnet pointing north. At the neutral point:
(a) the earth’s magnetic field is zero
(b) the magnet’s magnetic field is zero
(c) the fields of the magnet and the earth are equal and in the same direction
(d) the fields of the magnet and the earth are equal and opposite

Ans:d

15. Sudden fall of a barometer reading indicates:
(a) storm
(b) dry weather
(c) fine weather
(d) cold weather

Ans:a

16. If a ball and a rectangular block of different metal when completely immersed in a liquid, have the same loss of weight, then
(a) ball and rectangular block have same density
(b) ball and rectangular block have Weight in air
(c) ball and rectangular block have same volume
(d) ball and rectangular block have immersed to the same depth

Ans:c

17. If the period of oscillation of a simple pendulum is 4 seconds and we want to convert it into a second pendulum, then we have to:
(a) make the length of the pendulum one fourth of the previous length
(b) double the length of the pendulum
(c) make the length of the pendulum half of the previous length
(d) double the mass of the bob

Ans:a

18. The escape velocity of a body from the earth depends upon:
(a) mass of the body
(b) radius of the earth as well as the value of g
(c) the radius of the earth only
(d) volume of the body

Ans:b

19. A cyclist taking a turn bends inside because:
(a) he feels pleasure in doing so
(b) he increases speed in doing so
(c) he obtains necessary Centripetal force
(d) he avoids accidents
Ans:c

20. If the surface of water in a lake is just going to freeze, then the temperature of water at the bottom is
(a) 0°C
(b) 4°C
(c) 3°C
(d) none of these
Ans:b

21. The tangent law is applicable only when:
(a) there are at least two magnetic fields
(b) there two uniform magnetic fields mutually perpendicular to each other
(c) one strong magnetic field and the other weak magnetic field
(d) in the present magnetic fields one should be horizontal component of the earth’s magnetic field
Ans:b

22. A moving coil galvanometer is converted into an ammeter by putting:
(a) a high resistance in parallel
(b) a low resistance in series
(c) a low resistance in parallel
(d) a high resistance in series
Ans:c

23. Lenz’s law is derived from the law of conservation of:
(a)momentum
(b) energy
(c)charge
(d) magnetism
Ans:b

24. On which one of the factors does the sensivity of a galvanometer depend?
(a) number of the turns of the coil
(b) the temperature of the room
(c) the current flowing in it
(d) the potential difference between the two ends.
Ans:a

25. The wavelength of X-rays is of the order of:
(a) 0.1 cm
(b) 10 ²cm
(c)10 ^-4cm
(d)10 ^-8cm
Ans:d

26. Lamps used for street lighting are connected in
(a) parallel
(b) series and parallel both
(c) series
(d) none of the above
Ans:a

27. A. C. can be measured with the help of:
(a) moving coil galvanometer
(b) hot wire ammeter
(c) tangent galvanometer
(d) galvanometer

Ans:b

28.A p-n junction is said to be forward biased, when
(a) the positive pole of the battery is joined to the p-semiconductor and negative pole to the n-semiconductor
(b) the positive pole of the battery is joined to the n-semiconductor and negative pole of the battery is joined to the p-semiconductor
(c) the positive pole of the battery is connected to n- semiconductor and p- semiconductor
(d) a mechanical force is applied in the forward direction

Ans :a

29. At absolute zero, Si acts as ?

(a) non-metal
(b) metal
(c) insulator
(d) none of these

Ans :a

30. When N-type semiconductor is heated ?
(a) number of electrons increases while that of holes decreases
(b) number of holes increases while that of electrons decreases
(c) number of electrons and holes remain same
(d) number of electron and holes increases equally.
Ans :d

31. Radiowaves of constant amplitude can be generated with
(a) FET
(b) filter
(c) rectifier
(d) oscillator

Ans :d

32. In a common base amplifier the phase difference between the input signal voltage and the output
voltage is ?
(a) 0
(b) pi/4
(c)pi/2
(d) p
Ans :d
33. When a triode is used as an amplifier the phase difference between the input signal voltage and
the output is ?
(a) 0
(b)pi
(c) pi/2
(d)pi/4

Ans :b

34. The depletion layer in the P-N junction region is
caused by?
(a) drift of holes
(b) diffusion of charge carriers
(c) migration of impurity ions
(d) drift of electrons

Ans: b
35. The following truth table corresponds to which Logic gate

A	B	Output
0	0	0
0	1	1
1	0	1
1	1	1

(a)NAND
(b) OR
(c)AND
(d) XOR

Ans :b

36. To use a transistor as an amplifier
(a) The emitter base junction is forward biased and the base collector junction is reversed biased
(b) no bias voltage is required
(c) both junction are forward biased
(d) both junctions are reversed biased.

Ans :a

37. Which one of the following is the weakest kind of the bonding in solids
(a) ionic
(b) metallic
(c) Vander Walls
(d) covalent
Ans :c

38.For amplification by a triode, the signal to be amplified is given to
(a) the cathode
(b) the grid
(c) the glass-envelope
(d) the anode
Ans :b

39. A piece of copper and other of germanium are cooled from the room temperature to 80K, then

(a) resistance of each will increase
(b) resistance of copper will decrease
(c) the resistance of copper will increase while that of germanium will decrease
(d) the resistance of copper will decrease while that of germanium will increase
Ans:d

40. Diamond is very hard because ?
(a) it is covalent solid
(b) it has large cohesive energy
(c) high melting point
(d) insoluble in all solvents
Ans:b

41. The part of the transistor which is heavily doped to produce large number of majority carriers is

(a) emitter
(b) base
(c) collector
(d) any of the above depending upon the nature of transistor

Ans:a
42. An Oscillator is nothing but an amplifier with

(a) positive, feedback
(b) negative feedback
(c)large gain
(d) no feedback
Ans:a

43. When a P-N junction diode is reverse biased the flow of current across the junction is mainly due
to
(a) diffusion of charge
(b) drift charges
(c) depends on the nature o material
(d) both drift and diffusion of charges

Ans:b

44. Which of the following gates corresponds to the truth table given below?

A	B	Output
1	1	0
0	1	1
1	0	1
0	0	1

(a) NAND
(b) OR
(c) AND
(d) XOR

Ans:a

45. Which of the following, when added as an impurity, into the silicon, produces n-type semi conductor
(a)Phosphorous
(b) Aluminium
(c)Magnesium
(d) both ‘b’ and ‘c’

Ans:a

46. The current gain for a transistor working as common-base amplifier is 0.96. If the emitter current is 7.2 mA, then the base current is
(a)0.29mA
(b)0.35mA
(c)0.39 mA
(d) 0.43 mA

Ans:a
47. When a n-p-n transistor is used as an amplifier then ?
(a) the electrons flow from emitter to collector
(b) the holes flow from emitter to collector
(c) the electrons flow from collector to emitter
(d) the electrons flow from battery to emitter
Ans:a

48. When arsenic is added as an impurity to silicon, the resulting material is?
(a) n-type semiconductor
(b) p-type semiconductor
(c) n-type conductor
(d) Insulator

Ans:a

49. To obtain a p-type germanium semiconductor,it must be doped with ?
(a)arsenic
(b)antimony
(c)indium
(d)phosphorus
Ans:a

50. A semi-conducting device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops to almost zero. The device may be
(a) A p-n junction
(b) An intrinsic semi-conductor
(c) A p-type semi-conductor
(d) An n-type semi-conductor

Ans:a

51. The transfer ratio beta of a transistor is 50. The input resistance of the transistor when used in the common emitter configuration is 1 kOhm. The peak value of the co current for an A.C. input voltage of 0.01 V peak is ?
(a)100 microA
(b) 0.01 mA
(c)0.25 mA
(d) 500 microA
Ans:d

52. The cause of the potential barrier in a p-n diode is ?
(a) Depletion of positive charges near the junction
(b) Concentration of positive charges near the junction
(c) Depletion of negative charges near the junction
(d) Concentration of positive and negative charges near the junction
Ans:d

53. In forward bias, the width of potential barrier in a p-n junction diode?
(a)increases
(b) decreases
(c) remains constant
(d) first increases then decreases

Ans:b

54. A depletion lay consists of?
(a)electrons
(b) protons
(c)mobile ions
(d) immobile ions

Ans:d
55. Which of the following when added acts as an impurity into silicon produced n-type semi
conductor?
(a)P
(b) Al
(c)B
(d) Mg

Ans:a

56. In a junction diode, the holes are due to
(a) protons
(b) extra electrons
(c) neutrons
(d) missing electrons

Ans:d

57. The intrinsic semiconductor becomes an insulator at
(a)0°C
(b)0K
(c) 300K
(d) —100°C

Ans:b

58. For a common emitter circuit if I_C/I_E = 0.98 then current gain for common emitter circuit will be
(a)49
(b)98
(e)4.9
(d) 25.5
Ans:a

59. In a p-n junction
(a) The potential of the p and n sides becomes higher alternately
(b) The p side is at higher electrical potential than the n side
(c) The n side is at higher electrical potential than the p side
(d) Both the p and n sides are at the same potential

Ans:b

60. In the case of a common emitter transistor amplifier the ratio of the collector current to the emitter current I_c/I_e is 0.96. The current gain of the amplifier is ?
(a)6
(b)48
(c) 24
(d) 12

Ans:c

61. if a full wave rectifier circuit is operating from 5oHz mains, the fundamental frequency in the
tipple will be
(a)100Hz
(b) 25Hz
(c)50Hz
(d) 70.7 Hz

Ans:a
62. A n-p-n transistor conducts when ?
(a) both collector and emitter are negative with respect to, the base
(b) both collector and emitter are positive with respect to the base
(c) collector is positive and emitter is negative with to the base
(d) collector is positive and emitter is at same potential as the base

Ans:c

63. Barrier potential of a p-n junction diode does not depend on?
(a)doping density
(b) diode design
(c)temperature
(d) forward bias

Ans:b

64. Reverse bias applied to a junction diode
(a) increases the minority carrier current
(b) lowers the potential barrier
(c) raises the potential barrier
(d) increases the majority carrier current

Ans:c

65. In semiconductors at a room temperature

(a) the conduction band is completely empty
(b) the valence band is partially empty and the conduction band is partially filled
(c) the valence band is completely filled and the conduction band is partially filled
(d) the valence band is completely filled

Ans:c

66. The output of OR gate is 1 when?
(a) if either input is zero
(b) if both inputs are zero
(c) if either or both inputs are 1
(d) only if both inputs are I
Ans:c

67. In a p-n junction photo cell, the value of the photo-electromotive force produced by monochromatic light is proportional to ?
(a) the voltage applied at the p-n junction
(b) the barrier voltage at the p-n junction
(c) the intensity of the light falling on the cell
(d) the frequency of the light falling on the cell
Ans:c

68. Choose the only false statement from the following.
(a) in conductors the valence and conduction bands may overlap.
(b) Substances with energy gap of the order of 10 eV are insulators.
(c) The resistivity of a semiconductor increases with increase in temperature.
(d) The conductivity of a semiconductor increases with increase in temperature.

Ans:c

69. Carbon, Silicon and Germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by (E_g)_C, (E_g)_Si and (E_g)_Ge respectively. Which one of the following relationship is true in their case?
(a) (E_g)_C> (E_g)_Si
(b) (E_g)_C< (E_g)_Si
(c) (E_g)_C=(E_g)_Si
(d) (E_g)_C< (E_g)_Ge
Ans:a
70. Application of a forward bias to a p—n junction
(a) widens the depletion zone.
(b) increases the potential difference across the depletion zone.
(c) increases the number of donors on the n side.
(d) increases the electric field in the depletion zone.

Ans:c

71. Zener diode is used for?
(a) Amplification
(b) Rectification
(c) Stabilisation
(d) Producing oscillations in an oscillator

Ans:c

72. A current carrying coil is subjected to a uniform magnetic field. The coil will orient so that its
plane becomes ?
(a) inclined at 45° to the magnetic field
(b) inclined at any arbitrary angle to the
magnetic field
(c) parallel to the magnetic field
(d) perpendicular to magnetic field

Ans:c

73. Tesla is the unit of
(a) magnetic flux
(b) magnetic field
(c) magnetic induction
(d) magnetic moment
Ans:b

74. Energy in a current carrying coil is stored in the
form of ?
(a) electric field
(b) magnetic field
(c) dielectric strength
(d) heat

Ans:b

75. The total charge induced in a conducting loop when it is moved in magnetic field depends on?
(a) the rate of change of magnetic flux
(b) initial magnetic flux only
(c) the total change in magnetic flux
(d) final magnetic flux only.
Ans:c

76. The magnetic induction at a point P which is at the distance of 4 cm from a long current carrying wire is 10^-3 T. The field of induction at a distance 12 cm from the current will be ?
(a) 3.33 x 10^-4 T
(b) 1.11x 10^-4 T
(c) 3×10^-3 T
(d) 9×10^-3 T

Ans:a

77. A charge moving with velocity v in X-direction is subjected to a field of magnetic induction in negative X-direction. As a result, the charge will

(a) remain unaffected
(b) start moving in a circular path in Y—Z plane
(c) retard along X-axis
(d) moving along a helical path around X-axis
Ans:a

78. A uniform magnetic field acts right angles to the direction of motion of electrons. As a result, the electron moves in a circular path of radius 2cm. If the speed of electrons is doubled, then the radius of the circular path will be ?
(a)2.0 cm
(b) 0.5 cm
(c)4.0cm
(d) 1.0cm

Ans:c

79. A deuteron of kinetic energy 50 keV is describing a circular orbit of radius 0.5 metre in a plane perpendicular to magnetic field B. The kinetic energy of the proton that describes a circular orbit of radius 0.5 metre in the same plane with
the same B is
(a)25 keV
(b) 50 keV
(c)200 keV
(d) 100 keV

Ans:d

80. A straight wire of length 0.5 metre and carrying a current of 1.2 ampere is placed in uniform magnetic field of induction 2 Tesla. The magnetic field is perpendicular to the length of the wire. The force on the wire is ?
(a) 2.4N
(b) 1.2N
(c) 3.0 N
(d) 2.0 N
Ans:b

81. To convert a galvanometer into an ammeter, one needs to connect a ?
(a) low resistance in parallel
(b) high resistance in parallel
(c) low resistance in series
(d) high resistance in series.
Ans:a

82. A coil carrying electric current is placed in uniform magnetic field
(a) torque is formed
(B) e.m.f is induced
(c) both (a) and (b) are correct
(d) none of the above
Ans:a

83. The magnetic field at a distance ‘r’ from a long wire carrying current ‘i’ is 0.4 Tesla. The magnetic field at a distance ‘2r’ is ?
(a)0.2Tesla
(b) 0.8 Tesla
(c)0.1 Tesla
(d) 1.6 Tesla
Ans:a

84. A electron enters a region where magnetic (B) and electric (E) fields are mutually
perpendicular, then ?
(a) it will always move in the direction of B
(b) it will always move in the direction of E
(c) it always possesses circular motion
(d) it can go un deflected also.
Ans:d

85. A straight wire of diameter 0.5 mm carrying a current of 1 A is replaced by another wire of I mm diameter carrying same current. The strength of magnetic field far away is?
(a) twice the earlier value
(b) same as the earlier value
(c) one-half of the earlier value
(d) one-quarter of the earlier value

Ans:b

86. At what distance from a long straight wire carrying a current of 12 A will the magnetic field
be equal to 3×10^-6 Wb/metre Square
(a) 8×10^-2 m
(b) 12×10^-2 m
(c)18x 10^-2 m
(d) 24×10^-2 m

Ans:a

87. An electron moves in a circular orbit with a uniform speed v. It produces a magnetic field B at the centre of the circle. The radius of the circle is proportional to ?
(a) ?(B/v)
(b) B/v
(c) ?(v/B)
(d)v/B

Ans:d

88. A 10 eV electron is circulating in a plane at right angles to a uniform field at magnetic induction 10^-4 Wb/m² (= 1.0 gauss). The orbital radius of the electron is ?
(a) 12cm
(b) 16cm
(c) 11cm
(d) 18cm
Ans:c

89. A galvanometer acting as a voltmeter will have?

(a) a low resistance in series with its coil.
(b) a high resistance in parallel with its coil
(c) a high resistance in series with its coil
(d) a low resistance in parallel with its coil
Ans:c

90. A beam of electrons is moving with constant velocity in a region having simultaneous perpendicular electric and magnetic fields of strength 20 Vm^-1 and 0.5 T respectively at right angles to the direction of motion of the electrons. Then the velocity of electrons must be?
(a) 8m/s
(b) 20 m/s
(c) 40m/s
(d) 1/40 m/s

Ans:c

91. A galvanometer of resistance 20 Ohms gives full scale deflection with a current of 0.004 A. To convert it into an ammeter of range 1 A, the required shunt resistance should be?

(a) 0.38 Ohms
(b) 0.21 Ohms
(c) 0.08 Ohms
(d) 0.05 Ohms
Ans:c

92. A long solenoid carrying a current produces a magnetic field B along its axis. If the current is doubled and the number of turns per cm is halved, the new value of the magnetic field is ?
(a) 4B
(b) B/2
(c) B
(d) 2B
Ans:c

93. A positively charged particle moving due east enters a region of uniform magnetic field directed vertically upwards. The particle will
(a) continue to move due east
(b) move in a circular orbit with its speed unchanged
(c) move in a circular orbit with its speed increased
(d) gets deflected vertically upwards.

Ans:b
94. Two long parallel wires are at a distance of 1 metre. Both of them carry one ampere of current The force of attraction per unit length between the two wires is?
(a)2 x10^-7 N/m
(b) 2 x10^-8 N/m
(c) 5×10^-8 N/m
(d)10^-7 N/m

Ans:a

95. A galvanometer having a resistance of 8 ohms is shunted by a wire of resistance 2 ohms. If the total current is 1 amp, the part of it passing through the shunt will be?
(a)0.25 amp
(b) 0.8 amp
(c)0.2 amp
(d) 0.5 amp

Ans:b

96. A coil of one turn is made of a wire of certain length and then from the same length a coil of two turns is made. If the same current is passed in both the cases, then the ratio of the magnetic inductions at their centres will be?
(a)2:1
(b)1:4
(c)4:1
(d)1:2
Ans:b

97. Magnetic field intensity in the centre of coil of 50 turns, radius 0.5 m and carrying a current of
2A is ?
(a) 0.5 x 10^-5 T
(b) 1.25x 10^-4 T
(c) 3x 10^-5 T
(c) 4 x 10^-5 T

Ans:b

98. When a proton is accelerated through I V, then its kinetic energy will be?
(a)1840 eV
(b) 13.6eV
(c)1 eV
(d) 0.54eV

Ans:c

99. If a long hollow copper pipe carries a current,thin magnetic field is produced
(a)inside the pipe only
(b)outside the pipe only
(c)both inside and outside the pipe
(d) no where

Ans:b

100. A charged particle moves through a magnetic field in a direction perpendicular to it. Then the

(a) velocity remains unchanged
(b) speed of the particle remains unchanged
(c) direction of the particle remains unchanged
(d) acceleration remains unchanged
Ans:b

101. Which one of the following physical quantities, is not defined in the terms of force per unit area:
(a) pressure
(b) strain
(c) stress
(d) Young’s modulus

Ans:b

102. The distance moved by a moving body is equal to:
(a) area between the distance-time graph and distance axis
(b) area between the speed-time graph and time axis
(c) area between the distance-time graph and time axis
(d) area between the speed-time graph and distance axis.
Ans:b

103. A beaker containing water weighs 100 gm. It is placed on the pan of a balance and a piece of metal weighing 70 gm. and having a volume of 10cc. is placed inside the water in the beaker. The weight of the beaker and the metal would be :
(a) 170gm.
(c) 100gm.
(b)160gm.
(d)30gm.
Ans:a

104. For the same kinetic energy, the momentum shall be maximum for:
(a) electron
(b) proton
(c) deuteron
(d) alpha particle
Ans:d

105. The common balance works on the principle of equality of:
(a) forces
(b) moments of forces
(c) masses
(d) masses of pans
Ans:b

106. A particle moves in a circle of radius R with a constant speed under a centripetal force F. The work done in completing a full circle is:

(a) 2RF
(b) ?R²F
(c) 2?RF
(d)Zero

Ans:d
107. When two quantities are plotted on the graph paper against each other and the result so obtained is a st. line, then
(a) Both the quantities are equal
(b) The quantities are inversely proportional to each other
(c) Sum of both is zero
(d) The quantities are proportional to each other
Ans:d

108. What is the order of magnitude of 260°?
(a)10³
(b) 10⁴
(c)10²
(d) 10
Ans:c

109. The maximum value of g is:
(a) At the poles
(b) At the top of the Mount Everest
(c) At the equator
(d) Below the sea level
Ans:a

110. A fixed volume of gas at 27°C exerts a pressure of 750 mm. If the gas is heated to a pressure of 1500mm., temperature must be:
(a) 600°C
(b) 327°C
(c) 54°C
(d) 13.5°C
Ans:b

111. A body of mass 2 kg acted upon by a constant force, travels a distance of 3 metres in the first second and a further distance of meter in the next second. The force acting on the body is?
(a) 12 Newtons
(b) 8 Newtons
(c) 4 Newtons
(d) 1 Newton

Ans:c

112. Two forces each equal to P acting at a point have no resultant. The angle between the two forces must be equal to:
(a)180°
(b) 90°
(c)0°
(d) 120°

Ans:a

113. A jet engine works on the principle of:
(a) conservation of energy
(b) conservation of momentum
(c) conservation of mass
(d) conservation of temperature

Ans:b

114. A sharp knife cuts much better than a blunt one because?
(a) Area of sharp knife is much less than the area of the blunt one
(b) sharp knife is brighter
(c) sharp knife is colder
(d) sharp knife is costly
Ans:a

115. A man carries a heavy box on his head on a horizontal plane from one place to another.
In this he does?
(a) maximum work
(b) no work
(c) negative work
(d) minimum work
Ans:b

116. The bob of a second’s pendulum is replaced by another bob of double mass. The new time period will be:
(a) 4 sec.
(c) 2 sec.
(b) 1 sec
(d) 3 sec.

Ans:c

117.A device for measuring temperatures at a distance is
(a) gas thermometer
(b) mercury thermometer
(c) radiation
(d) maximum-minimum thermometer

Ans:c

118. A piece of ice is floating in a concentrated solution of common salt (in water) in a pot. When ice melts completely, the level of solution will:
(a) go up
(b) remain the same
(c) go down
(d) first go up then go down

Ans:a

119. A radioactive source has a half-life of 30 days. During a period of 90 days the fraction of atoms that have decayed would be
(a)100%
(b) 87.5%
(c)64%
(d) 50%

Ans:b

120. A black body emits:
(a) radiations of all wavelengths
(b) no radiations
(c) radiations of only one wavelength
(d) radiations of selected wavelengths

Ans:a

121. A near sighted person cannot see distinctly beyond 50 cm. from his eye. The power in diopter of spectacle lenses which will enable him to see distant objects clearly is
(a) +50
(b) —50
(c) +2
(d) —2
Ans:c

122. Size of a nucleus is of the order of?
(a)10^-18m
(b) 10^-14m
(c)10^-10m
(d) 10^-6m
Ans:b

123. The freezing point on a thermometer is marked as 20° and the boiling point as 150°C. A temperature of 60°C on this thermometer will be read as:
(a)40°
(b) 65°
(c)98°
(d) 110°
Ans:c

124. In isothermal expansion of an ideal gas:
(a) heat content remains constant
(b) temperature remains constant
(c) both heat content and temperature remain constant
(d) pressure and temperature of the gas remain constant
Ans:b

125. A man standing between two cliffs hears the first echo of a sound after 2 sec. and the second echo 3 sec. after the initial sound. If the speed of sound be 330 m/sec. the distance between the two cliffs should be
(a)1650 m.
(b)990 m.
(c)825 m
(d) 660 m.
Ans:c

126. In a resonance tube experiment the first resonance is obtained for 10 cm. of air column and the second for 32 cm. The end correction for this apparatus is equal to?
(a)0.5 cm
(b)1.0 cm
(c)1.5 cm
(d) 2 cm
Ans:b

127. The ratio of the specific heat of air at constant pressure to its specific heat at constant volume is?
(a) zero
(b) greater than one
(c) less than one
(d) equal to one

Ans:b

128. A convex lens has a focal length of 10 cm. When it is immersed in water it will behave
as?
(a) a convex tens of 10 cm. focal length
(b) a concave lens of 10 cm. focal length
(c) a convex lens of focal length greater than 10cm.
(d) a convex lens of focal length less than 10 cm.
Ans:c
129. Two particles having charges q1 and q2 when kept at a certain distance exert a force F on each other. If the distance between the two particles is reduced to half and the charge on each particle is doubled the force between the particles would be ?
(a)2F
(b)4F
(c)8F
(d)16F
Ans:d

130. A small magnet is placed perpendicular to a constant magnetic field. The forces acting on the magnet will result in?
(a) rotation
(b) translation
(c) no motion at all
(d) rotation as well as translation
Ans:a

131. A hollow metallic sphere is charged. Inside the sphere?
(a) the potential is zero but the electric field is finite
(b) the electric field is zero but the potential is finite
(c) both the electric field and the potential are finite
(d) both the electric field and the potential are zero
Ans:b

132. Two electric lamps each of 100 watts 220 V are connected in series to a supply of 220 volts. The power consumed would be:
(a)100 Watts
(b) 200 Watts
(c)25 Watts
(d) 50 Watts
Ans:d

133. A transformer is:
(a) a device for stepping up D.C.
(b) a generator of current
(c) device for converting direct current into alternating current
(d) a device for stepping up or down the voltage of A.C. supply
Ans:d

134. Transistor act as a?
(a) conductor
(b) semi-conductor
(c) insulator
(d) thermionic valve

Ans:d

135. The sky is blue because:
(a) there is more blue light in the sunlight
(b) of scattering of sunlight by air molecules in the atmosphere
(c) of scattering of sunlight by dust particles in the atmosphere
(d) other colours are absorbed by heavenly bodies
Ans:b

136. A cyclonic storm is indicated by a change in the atmospheric pressure. In atmospheric
pressure there is a:
(a)sudden rise
(b) gradual rise
(c)sudden fall
(d) gradual fall
Ans:c

137. The electric field inside a hollow conducting sphere will ?
(a) increases towards the centre
(b) decreases towards the centre
(c) is finite and constant throughout
(d) is zero
Ans:d

138. Imperfect gases are those:
(a) which contain impurities
(b) which do not obey Charle’s and Boyle’s laws
(c) whose molecules are not spherical
(d) whose molecules cannot be regarded as point masses
Ans:b

139. Sonar is a device for:
(a) location and ranging of aircraft’s
(b) location and ranging submarines
(c) producing a musical note of high quality
(d) measuring frequency of musical notes
Ans:b

140. Cyclotron is a device to produce:
(a) atomic energy
(b) high energy electrons
(c) high energy photons
(d) high energy protons
Ans:d

141. Which one of the following is not a vector?
(a) Velocity
(b) Acceleration
(c) Force
(d) Energy
Ans:d

142. Two steel balls of mass 1 kg. and 2kg. and a lead ball of 10kg. are released together from the top of tower 30 metres high. Assuming the path to be in vacuum
(a) the lead ball reaches the ground earlier
(b) the 1 kg. steel bail reaches the ground earlier
(c) all the balls reach the ground simultaneously
(d) the 2 kg. steel ball reaches the ground earlier
Ans:c

143. After a watch has been wound, it?
(a) has great energy stored in it
(b) possesses mechanical potential energy stored in it
(c) has eletrical energy stored in it
(d) has no energy in it
Ans:b

144. Two plane mirrors are set at right angles and a flower is placed in any position in between the mirrors. The number of images of the flower which will be seen is?
(b) two
(d) four
(a) one
(c) three
Ans:c

145. In which of the following cases total internal reflection cannot be obtained?
(a) ray going from water to glass
(b) a ray going from glass to water
(c) a ray going from glass to air
(d) a ray going from water to air.
Ans:a

146. When white light passes through a glass prism, we get a spectrum on the other side of the prism. In the emergent beam the ray which is deviated least is
(a) the violet ray
(b) the red ray
(c) the green ray
(d) the yellow ray
Ans:b

147. Magnetic storms are due to
(a) the rotation of the earth
(b) the revolution of the earth
(c) the rainy season
(d) the appearance off Sun spots
Ans:d

148. For dynamo which one of the following statements is correct ?
(a) It converts the electrical energy into light energy
(b) It converts the kinetic energy into heat energy
(c) It converts the mechanical energy into electrical energy
(d) Jt converts the electrical energy into mechanical energy.
Ans:c

149. In a transformer the immediate cause of the induced A. C. in the secondary coil is?
(a) a varying electric field
(b) a varying magnetic field
(e) a motion of the secondary coil
(d) efficiency of the operator
Ans:b

150.A dynamo actually acts as a?
(a) converter of energy
(b) source of electric charge
(c) source of magnetic charge
(d) source of energy
Ans:a

151. Two long parallel wires P and Q are both perpendicular to the plane of the paper with distance of 5 m between them. If P and Q carry current of 2.5 amp and 5 amp respectively in the same direction, then the magnetic field at a point half-way between the wires is ?

(a)3µ/2?
(b)µ/?
(c)?3µ/2?
(d)µ/2?
Ans:a

152. A proton moving with a velocity 3 x 10⁵ m/s enters a magnetic field of 0.3 Tesla at an angle of 30° with the field. The radius of curvature of its path will be (e/m for proton – 10⁸ C/kg)
(a)2cm
(b) 0.5 cm
(c)0.02 cm
(d) 1.25 cm

Ans:b

153. A charged particle of charge q and mass m enters perpendicularly in a magnetic field B. Kinetic energy of the particle is E; then frequency of rotation is?
(a)qB/m∏
(b) qB/2m∏
(c)qBE/2m∏
(d) qB/2E∏

Ans:b

154. A galvanometer can be converted into a voltmeter by connecting?
(a) A high resistance in parallel
(b) A low resistance in series
(c) A high resistance in series
(d) A low resistance in parallel
Ans:c

155. A wire carries a current. Maintaining the same current it is bent first to form a circular plane coil of one turn which produces a magnetic field B at the centre of the coil. The same length is now bent more sharply to give a double loop of smaller radius. The magnetic field at the centre of the double loop, caused by the same current is ?
(a)4B
(b) B /4
(c) B/2
(d) 2B
Ans:a

156.A bar magnet is oscillating in earth’s magnetic field with a period T. What happens to its period of motion, if its mass is quadruped ?
(a) Motion remains simple harmonic with new period =T/2
(b) Motion remains simple harmonic with new period = 2 T
(c) Motion remains simple harmonic with new period =4T
(d) Motion remains simple harmonic and the period stays nearly constant
Ans:b

157. The work done in turning a magnet of magnetic moment M by an angle of 90° from the meridian, is n times the corresponding work done to turn it through an angle of 60°.
The value of n is given by
(a)2
(b) 1
(c) 0.5
(d) 0.25
Ans:a

158 . For protecting a sensitive equipment from the external electric arc, it should be ?
(a) Wrapped with insulation around it when passing current through it
(b) Placed inside an iron can
(c) Surrounded with fine copper sheet
(d) Placed inside an aluminium can
Ans:b

159. If a diamagnetic substance is brought near north or south pole of a bar magnet, it is?
(a) attracted by the poles
(b) repelled by the poles
(c) repelled by north pole and attracted by the south pole
(d) attracted by the north pole and repelled by the south pole

Ans:b

160. Current i is flowing in a coil of area A and number of turns N, then magnetic moment of
the coil is M= ?

(a) NiA
(b) Ni/A
(c)Ni/?A
(d) N²Ai

Ans:a

161. Two magnets of magnetic moments M and 2M are placed in a vibration magnetometer, with the identical poles in the same direction. The time period of vibration is T₁. If the magnets are placed with opposite poles together and vibrate with time period T₂ then ?
(a) T₂ is infinite
(b) T₂=T₁
(c)T₂>T₁
(d) T₂ is less than T₁

Ans:c
162. A diamagnetic material in a magnetic field moves
(a) perpendicular to the field
(b) from stronger to the weaker pans of the field
(c) from weaker to the stronger parts of the field
(d) in none of the above directions
Ans:b
163. According to Curie’s law, the magnetic susceptibility of a substance at an absolute
temperature T is proportional to?
(a) T²
(b) 1/T
(c) T
(d) 1/T²

Ans:b