Question

A $200\, W$ and a $100 \, W$ bulb, both. meant for operation at $220 \, V$ are connected in series. When connected to a $220 \, V$ supply the power consumed by the, combination is

• A. 33.3 W
• B. 66.7 W
• C. 300 W
• D. 100 W

Answer 1

Answer: (B)

When two similar bulbs of different powers are connected in series, then
$\frac{1}{P}=\frac{1}{P_{1}}+\frac{1}{P_{2}}$
Given, $P_{1}=200\, W$
$P_{2}=100\, W$
$\Rightarrow \frac{1}{P}=\frac{1+2}{200}$
$\Rightarrow $ S $P=\frac{200}{3}=66.7\, W$