Question

A 220 V, 100 W bulb is connected to a 110 V source. Calculate the power consumed by the bulb.

• A. 10 W
• B. 15 W
• C. 20 W
• D. 25 W

Answer 1

Answer: (D)

25 W

$P=100W$

$V=220V$

We know

$P=\frac{V^2}{R}$

So

$R=\frac{V^2}{P}$=$\frac{{220}^2}{100}$=$484\Omega$

Supply=$V=110V$

$P=\frac{V^2}{R}$

$P=\frac{{110}^2}{484}$=$25W$