Chap#13 Current Electricity

Question 1

A ten-ohm electric heater operates on a 110 V line Clculate the rate at which it develops heat in watts:

Answer 1

1210 W

Question 2

Two electric bulbs of 200 W and 100 W have same voltage. If R1 and R2 be their resistance respectively then:

Answer 2

R2 = 2R1

Question 3

A wire of radius r has resistance R. If it is stretched to a wire of r/2 radius, then the resistance becomes:

Answer 3

16 R

Question 4

A (100W, 200 V) bulb is connected to a 160 V power supply. The power consumption would be:

Answer 4

64 W

Question 5

A 50-volt battery is connected across 10-ohm resistor. The current is 4.5 A. The internal resistance of the battery is:

Answer 5

1.1 Ω

Question 6

If 2.2 kilowatt power is transmitted through a 10 ohm line at 22000 volt, the power loss in the form of heat will be:

Answer 6

0.1 watt

Question 7

The conductivity of a superconductor is:

Answer 7

Infinite

Question 8

A piece of fuse wire melts when a current of 15 ampere flows through it. With this current, if it dissipates 22.5 W, the resistance of fuse wire will be:

Answer 8

0.10 Ω

Question 9

A conducting wire is drawn to double its length. Final resistivity o the material will be:

Answer 9

Same as original value

Question 10

In a voltmeter the conduction takes place due to:

Answer 10

Electrons only