Question

In the circuits shown, all the cells are identical. One bulb requires one cell to light up to normal brightness. In which circuit do the bulbs not light up to normal brightness?

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

a. Both the bulbs are in parallel with the cell. Therefore, the power of the cell across each of them is the same. Therefore, both the bulbs will be lit to normal brightness.

b. Although this circuit contains two cells in parallel, the net effect will be the same as one cell. Therefore the bulb will be lit to normal brightness.

c. This circuit contains 2 bulbs and a 2 cell battery. The net effect across each of the bulbs will be equal to that of a single cell because the bulbs are in series.

d. This circuit contains two bulbs in series across a battery. Therefore, the power of the cell will divide across each bulb. Therefore, the bulbs will not light up to normal brightness.