Question

$n$ identical bulbs, each designed to draw power $P$ from a certain source are joined in series across that supply. The total power drawn is

• A. $\frac{P}{n^2}$
• B. $\frac{p}{n}$
• C. P
• D. n P

Answer 1

Answer: (B)

Resistance of each bulb, R = $\frac{V^2}{P}$ and Resistance of $n$ bulbs in series = $n$R = $\frac{nV^2}{P}$
$\therefore $ Power drawn when n bulbs are in serie = $\frac{V^2}{n \times \frac{V^2}{P}} = \frac{P}{n}$