Question

An electric bulb is rated 220V and 100W. When it is operated on 110V,What will be the power consumed?

Answer it by finding current and resistance and by using both answer this question

Answer 1

Case 1

$p = v {}^{2} \div r$


$= 220 \times 220 \div 100 = 484 \: ohm$
$p = v {}^{2} \div r$
$= 110 \times 110 \div 484 = 25 \: watt$