Question

An electric bulb is rated as 250 V, 750 W. Calculate the:

1. Electric current flowing through it, when it is operated on a 250 V supply.
2. Resistance of its filament.

Answer 1

Given: V = 250 V

P = 750 W

I = ?

R = ?

i. P = VI

⇒ I = `P/V`

= `750/250`

= 3 A

ii. P = I²R

⇒ R = `P/I^2`

= `750/9`

= 83.33 Ω