Current Electricity Book Back Questions & Answers
Unit 2 > Physics > Class 12 > Samacheer Kalvi - English Medium
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1. The following graph shows current versus voltage values of some unknown conductor. What is the resistance of this conductor?
(a) 2 ohm
(b) 4 ohm
(c) 8 ohm
(d) 1 ohm
Correct answer: (a) 2 ohm
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2. . A wire of resistance 2 ohms per meter is bent to form a circle of radius 1m. The equivalent resistance between its two diametrically opposite points, A and B as shown in the figure is
(a)
(b) 2
(c) 2
(d) 4
Correct answer: (b) 2
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3. A toaster operating at 240 V has a resistance of 120 . Its power is
(a) 400 W
(b) 2 W
(c) 480 W
(d) 240 W
Correct answer: (c) 480 W
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4. A carbon resistor of (47 4.7 ) k to be marked with rings of different colours for its identification. The colour code sequence will be
(a) Yellow Green Violet Gold
(b) Yellow Violet Orange Silver
(c) Violet Yellow Orange Silver
(d) Green Orange Violet Gold
Correct answer: (b) Yellow Violet Orange Silver
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5. What is the value of resistance of the following resistor?
(a) 100 k
(b) 10 k M
(c) 1 k
(d) 1000 k
Correct answer: (a) 100 k
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6. Two wires of A and B with circular cross section are made up of the same material with equal lengths. Suppose RA = 3 RB, then what is the ratio of radius of wire A to that of B?
(a) 3
(b) 3
(c) 13
(d) 13
Correct answer: (c) 13
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7. A wire connected to a power supply of 230 V has power dissipation P1 . Suppose the wire is cut into two equal pieces and connected parallel to the same power supply. In this case power dissipation is P2 . The ratio P P 2 1 is
(a) 1
(b) 2
(c) 3
(d) 4
Correct answer: (d) 4
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8. In India electricity is supplied for domestic use at 220 V. It is supplied at 110 V in USA. If the resistance of a 60W bulb for use in India is R, the resistance of a 60W bulb for use in USA will be
(a) R
(b) 2R
(c) R4
(d) R2
Correct answer: (c) R4
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9. In a large building, there are 15 bulbs of 40 W, 5 bulbs of 100 W, 5 fans of 80 W and 1 heater of 1kW are connected. The voltage of electric mains is 220 V. The maximum capacity of the main fuse of the building will be
(a) 14 A
(b) 8 A
(c) 10 A
(d) 12 A
Correct answer: (d) 12 A
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10. There is a current of 1.0 A in the circuit shown below. What is the resistance of P ?
(a) 1.5
(b) 2.5
(c) 3.5
(d) 4.5
Correct answer: (c) 3.5
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11. What is the current drawn out from the battery?
() 1 A
(b) 2 A
(c) 3 A
(d) 4 A
Correct answer: () 1 A
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12. The temperature coefficient of resistance of a wire is 0.00125 per C. At 20C, its resistance is 1 . The resistance of the wire will be 2 at
a) 800 C
b) 700 C
c) 850 C
d) 820 C
Correct answer: d) 820 C
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13. The internal resistance of a 2.1 V cell which gives a current of 0.2 A through a resistance of 10 is
(a) 0.2
(b) 0.5
(c) 0.8
(d) 1.0
Correct answer: (b) 0.5
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14. A piece of copper and another of germanium are cooled from room temperature to 80 K. The resistance of
(a) each of them increases
(b) each of them decreases
(c) copper increases and germanium decreases
(d) copper decreases and germanium increases
Correct answer: (d) copper decreases and germanium increases
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15. In Joules heating law, when R and t are constant, if the H is taken along the y axis and I2 along the x axis, the graph is
(a) straight line
(b) parabola
(c) circle
(d) ellipse
Correct answer: (a) straight line