Electrical Test Questions and Answers

61. What voltage drop will be there across a 1 kW electric heater whose resistance when hot is 40 Ω ?

(i) 109 V
(ii) 50 V
(iii) 150 V
(iv) 200 V

62. A resistor R₁ dissipates the power P when connected to a certain generator. If resistance R₂ is put in series with R₁, the power dissipated by R₁

(i) decreases
(ii) increases
(iii) remains the same
(iv) any of the above depending upon the values of R₁ and R₂

63. In case of liquids, ohm’s law is

(i) fully obeyed
(ii) partially obeyed
(iii) there is no relation between current and p.d.
(iv) none of the above

64. Two electric bulbs rated for the same voltage have powers of 200 W and 100 W. If their resistances are respectively R₁ and R₂, then,

(i) R₁ = 2R₂
(ii) R₂ = 2R₁
(iii) R₂ = 4 R₁

65. A copper wire has a resistance of 10 Ω. It is stretched by one-tenth of its original length. Then its resistance will be

(i) 10 Ω
(ii) 12.1 Ω
(iii) 9 Ω
(iv) 11 Ω

66. The current-voltage graphs for a given metallic wire at two different temperatures T₁, and T₂ are shown in Fig. 3. Then

(i) T₂ > T₁
(ii) T₂ < T₁
(iii) T₁ = T₂
(iv) none of the above

67. 10²⁰ electrons each having a charge of 1.6 x 10^-19C pass from a point X to a point Y in 0.1 s. The current Flowing is

(i) 16A
(ii) 1.6 A
(iii) 160 A
(iv) 1 A

68. No current flows between two charged bodies if they have same

(i) capacity
(ii) potential
(iii) charge
(iv) none of the above

69. A carbon electrode has a resistance of 0.125 Ω at 20°C. The temperature coefficient of carbon is -0.0005 at 20°C. What will be the resistance of electrode at 85°C ?

(i) 4 Ω
(ii) 0.5 Ω
(iii) 1.2 Ω
(iv) 0.121 Ω

70. The specific resistance of a wire 1.1 m long, 0.4 mm diameter having a resistance of 4.2 Ω will be

(i) 48 x 10^-8 Ωm
(ii) 40 x 10⁸ Ωm
(iii) 4 x 10^-6 Ωm
(iv) none of the above

71. Which of the following is the best material for making connecting wires ?

(i) manganin
(ii) constantan
(iii) copper
(iv) nichrome

72. The specific resistance of the material of wire depends on

(i) the area of cross-section
(ii) length
(iii) mass
(iv) none of the above

73. Ampere – second is the unit of

(i) power
(ii) energy
(iii) e.m.f.
(iv) charge

75. What will be the resistance value corresponding to colour code yellow, violet, orange, silver ?

(i) 47 kΩ ± 10%
(ii) 4.7 kΩ ± 20 %
(iii) 2 kΩ ± 10%
(iv) none of the above

76. What will be the resistance value corresponding to colour code brown, black, red ?

(i) 2 kΩ ± 10%
(ii) 1 kΩ ± 20 %
(iii) 7 kΩ ± 20 %
(iv) none of the above

77. Two resistors A and B have resistances R_A and R_B respectively with R_A < R_B. The resistivities of their materials are ρ_A and ρ_B. Then

(i) ρ_A > ρ_B
(ii) ρ_A = ρ_B
(iii) ρ_A < ρ_B
(iv) Information insufficient

78. As the temperature of a metallic resistor is increased, the product of its resistivity and conductivity

(i) increases
(ii) decreases
(iii) remains constant
(iv) may increase or decrease

79. A resistor develops 400 J of thermal energy in 10 s when a current of 2 A is passed through it. The resistance of the resistor is

(i) 10 Ω
(ii) 20 Ω
(iii) 5 Ω
(iv) 40 Ω

80. An electron moves in a circle of radius 10 cm with a constant speed of 4 x 10⁶ ms^-1. The electric current at a point on the circle is

(i) 1 x 10^-12A
(ii) 4 x 10^-7A
(iii) 2 x 10^-6A
(iv) none of above

81. The resistance of human body is about

(i) 200 Ω
(ii) 10 Ω
(iii) 1000 Ω
(iv) 25 Ω

83. The hot resistance of electric bulb’s filament is higher than its cold resistance because the temperature co-efficient of filament is

(i) zero
(ii) positive
(iii) negative
(iv) none of above

84. A nichrome wire used as a heater coil has a resistance of 2 Ω/m. For a heater of 1 kW at 200 V, the length of the wire required is

(i) 80m
(ii) 40m
(iii) 20m
(iv) 24m

85. When 1 V is applied in a circuit a current of 1 µA flows through it. The conductance of the circuit is

(i) 1 µ mho
(ii) 10⁶ mho
(iii) 2 µ mho
(iv) none of above

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