Answer: (iii) 9 times

### 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

Answer: (iv) 200 V

### 62. A resistor R_{1} dissipates the power P when connected to a certain generator. If resistance R_{2} is put in series with R_{1}, the power dissipated by R_{1}

(i) decreases

(ii) increases

(iii) remains the same

(iv) any of the above depending upon the values of R_{1} and R_{2}

Answer: (i) decreases

### 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

Answer: (i) fully obeyed

### 64. Two electric bulbs rated for the same voltage have powers of 200 W and 100 W. If their resistances are respectively R_{1} and R_{2}, then,

(i) R_{1} = 2R_{2 }

(ii) R_{2 }= 2R_{1}

(iii) R_{2 }= 4 R_{1}

Answer: (ii) R

_{2 }= 2R

_{1}

### 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

Answer: (ii) 12.1 Ω

### 66. The current-voltage graphs for a given metallic wire at two different temperatures T_{1}, and T_{2} are shown in Fig. 3. Then

(i) T_{2 }> T_{1}

(ii) T_{2} < T_{1}

(iii) T_{1} = T_{2}

(iv) none of the above

Answer: (i) T

_{2 }> T

_{1}

### 67. 10^{20} electrons each having a charge of 1.6 x 10^{-19}C 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

Answer: (iii) 160 A

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

(i) capacity

(ii) potential

(iii) charge

(iv) none of the above

Answer: (ii) potential

### 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

Answer: (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 10^{8} Ωm

(iii) 4 x 10^{-6} Ωm

(iv) none of the above

Answer: (i) 48 x 10

^{-8}Ωm

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

(i) manganin

(ii) constantan

(iii) copper

(iv) nichrome

Answer: (iii) copper

### 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

Answer: (iv) none of the above

### 73. Ampere – second is the unit of

(i) power

(ii) energy

(iii) e.m.f.

(iv) charge

Answer: (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

Answer: (i) 47 kΩ ± 10%

### 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

Answer: (ii) 1 kΩ ± 20 %

### 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

Answer: (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

Answer: (iii) remains constant

### 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

Answer: (i) 10 Ω

### 80. An electron moves in a circle of radius 10 cm with a constant speed of 4 x 10^{6} ms^{-1}. The electric current at a point on the circle is

(i) 1 x 10^{-12}A

(ii) 4 x 10^{-7}A

(iii) 2 x 10^{-6}A

(iv) none of above

Answer: (i) 1 x 10

^{-12}A

### 81. The resistance of human body is about

(i) 200 Ω

(ii) 10 Ω

(iii) 1000 Ω

(iv) 25 Ω

Answer: (iii) 1000 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

Answer: (ii) positive

### 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

Answer: (iii) 20m

### 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) 10^{6 }mho

(iii) 2 µ mho

(iv) none of above

Answer: (i) 1 µ mho

Thanks for reading about “electrical test questions and answers”.