test quiz

1. A cylindrical conductor of length l and uniform area of cross-section A has a resistance R. Another conductor of length 2l and resistance R of the same material has an area of cross-section:

A/2 2A A 4A

2. Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be:

1:2 2:1 1:4 4:1

3. An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be:

100 W 75 W 50 W 25 W

4. What happens to the total circuit resistance and current when more resistors are added in a parallel combination across a fixed voltage source?

Total resistance increases and current decreases. Total resistance decreases and current increases. Both total resistance and current increase. Total resistance decreases and current remains the same.

5. If a wire is stretched to double its length without changing its mass, its resistivity will:

Become double Become four times Remain unchanged Become one-fourth