Question

A 75 watt bulb draws 680 mA how much time will be required to pass 30 columb change through the bulb

Answer 1

Explanation:

P = 75W

I = 680 mA = 680/1000 A

q = 30 coulombs

P = VI

=> V = 75 x 1000 / 680

=> V = 110V ( rounded off)

W = qV

= 30 x 110

= 3300J

T = W/P

= 3300 / 75

= 44 seconds ( approx)

Or you can directly do it this way :-

t = q/I

= 30 x 1000 / 680

= 44 seconds ( approx)