51. Which of the following quantities remain the same in all parts of a series circuit ?
(a) Voltage
(b) Current
(c) Power
(d) Resistance
Ans: b
52. A 40 W bulb is connected in series with a room heater. If now 40 W bulb is replaced by 100 W bulb, the heater output will
(a) decrease
(b) increase
(c) remain same
(d) heater will burn out
Ans: b
53. In an electric kettle water boils in 10 m minutes. It is required to boil the boiler in 15 minutes, using same supply mains
(a) length of heating element should be decreased
(b) length of heating element should be increased
(c) length of heating element has no effect on heating if water
(d) none of the above
Ans: a
54. An electric filament bulb can be worked from
(a) D.C. supply only
(b) A.C. supply only
(c) Battery supply only
(d) All above
Ans: d
55. Resistance of a tungsten lamp as applied voltage increases
(a) decreases
(b) increases
(c) remains same
(d) none of the above
Ans: b
56. Electric current passing through the circuit produces
(a) magnetic effect
(b) luminous effect
(c) thermal effect
(d) chemical effect
(e) all above effects
Ans: c
57. Resistance of a material always decreases if
(a) temperature of material is decreased
(6) temperature of material is increased
(c) number of free electrons available become more
(d) none of the above is correct
Ans: c
58. If the efficiency of a machine is to be high, what should be low ?
(a) Input power
(b) Losses
(c) True component of power
(d) kWh consumed
(e) Ratio of output to input
Ans: b
59. When electric current passes through a metallic conductor, its temperature rises. This is due to
(a) collisions between conduction electrons and atoms
(b) the release of conduction electrons from parent atoms
(c) mutual collisions between metal atoms
(d) mutual collisions between conducting electrons
Ans: a
60. Two bulbs of 500 W and 200 W rated at 250 V will have resistance ratio as
(a) 4 : 25
(b) 25 : 4
(c) 2 : 5
(d) 5 : 2
Ans: c
61. A glass rod when rubbed with silk cloth is charged because
(a) it takes in proton
(b) its atoms are removed
(c) it gives away electrons
(d) it gives away positive charge
Ans: c
62. Whether circuit may be AC. or D.C. one, following is most effective in reducing the magnitude of the current.
(a) Reactor
(b) Capacitor
(c) Inductor
(d) Resistor
Ans: d
63. It becomes more difficult to remove
(a) any electron from the orbit
(6) first electron from the orbit
(c) second electron from the orbit
(d) third electron from the orbit
Ans: d
64. When one leg of parallel circuit is opened out the total current will
(a) reduce
(b) increase
(c) decrease
(d) become zero
Ans: c
65. In a lamp load when more than one lamp are switched on the total resistance of the load
(a) increases
(b) decreases
(c) remains same
(d) none of the above
Ans: b
66. Two lamps 100 W and 40 W are connected in series across 230 V (alternating). Which of the following statement is correct ?
(a) 100 W lamp will glow brighter
(b) 40 W lamp will glow brighter
(c) Both lamps will glow equally bright
(d) 40 W lamp will fuse
Ans: b
67. Resistance of 220 V, 100 W lamp will be
(a) 4.84 Q
(b) 48.4 Q
(c) 484 ft
(d) 4840 Q
Ans: c
68. In the case of direct current
(a) magnitude and direction of current remains constant
(b) magnitude and direction of current changes with time
(c) magnitude of current changes with time
(d) magnitude of current remains constant
Ans: a
69. When electric current passes through a bucket full of water, lot of bubbling is observed. This suggests that the type of supply is
(a) A.C.
(b) D.C.
(c) any of above two
(d) none of the above
Ans: b
70. Resistance of carbon filament lamp as the applied voltage increases.
(a) increases
(b) decreases
(c) remains same
(d) none of the above
Ans: b
71. Bulbs in street lighting are all connected in
(a) parallel
(b) series
(c) seriesparallel
(d) endtoend
Ans: a
72. For testing appliances, the wattage of test lamp should be
(a) very low
(b) low
(c) high
(d) any value
Ans: c
73. Switching of a lamp in house produces noise in the radio. This is because switching operation produces
(a) arcs across separating contacts
(b) mechanical noise of high intensity
(c) both mechanical noise and arc between contacts
(d) none of the above
Ans: a
74. Sparking occurs when a load is switched off because the circuit has high
(a) resistance
(b) inductance
(c) capacitance
(d) impedance
Ans: b
75. Copper wire of certain length and resistance is drawn out to three times its length without change in volume, the new resistance of wire
becomes
(a) 1/9 times
(b) 3 times
(e) 9 times
(d) unchanged
Ans: c
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Oleh
TNPSC Master
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