Question

An electric bulb is rated 220V, 100 W (a) What is its resistance ? (b) What safe current can be passed through it?

Answer 1

a)

P = 100 Watt

V = 220 V

then , P =

$\Rightarrow$ R = 22 $\times$ 22 = 484 Ohm

b) V = I $\times$ R

I = $\frac{220}{484}$ = $\frac{5}{11}$

= 0.45 A