Question

A boy has two spare light bulbs in his drawer. One is marked 240 V and 100 W and the other is marked 240 V and 60 W. He tries to decide which of the following assertions are correct?

• A. The 60 W light bulb has more resistance and therefore burns less brightly.
• B. The 60 W light bulb has less resistance and therefore burns less brightly.
• C. The 100 W bulb has more resistance and therefore burns more brightly.
• D. The 100 W bulb has less resistance and therefore burns less brightly.

Answer 1

Answer: (A)

The 60 W light bulb has more resistance and therefore burns less brightly.

Answer 2

: When the same potential difference, that is the voltage, is applied as in houses,

$= VI = \frac{V^{2}}{R}.$

The smaller resistance consumes greater power. Here 100 W bulb has less resistance. It should glow more brightly. The 60 W bulb has more resistance and therefore statement (1) is correct.