Question

If a 9V, 7W radio is on from 9am to 12pm. Calculate the amount of charge that flows through it, hence or otherwise the total number of free electrons that pass through at a point at the power supply terminals​

Answer 1

Q=It

and

p=IV

Given, v=9V P= 7W

I=P/V

I =7/9

Also, time(t) from 9am to 12pm is 3hrs

Converting into sec =3×3600

t=10800

Q= 7/9 ×10800

Q =8400C