Question

Calculate the current through a $60$ W lamp rated for $250$ V. the line voltage falls to $200$ V, how is the power consumed by the lamp effected?

Answer 1

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

$R=\frac{V^2}{P}=\frac{(250\times 250)}{60}=1041.67$

power consumed by bulb $\frac{{200}^2}{1041.67}=38.40W$

$60$ watt bulb act as a $38.40W$ bulb