Question

A 220 volt, 1000 W bulb is connected across a 110 volt mains supply. The power consumed will be

• A. 1000 W
• B. 750 W
• C. 500 W
• D. 250 W

Answer 1

Answer: (D)

250 W

Answer 2

$\frac{P_{1}}{P_{2}} = \left( \frac{V_{1}}{V_{2}} \right)^{2} \Rightarrow \frac{1000}{P_{2}} = \left( \frac{220}{110} \right)^{2} = 4$⇒ $P_{2} = 250W$