Question

Find the number of particles each carrying the charge of an electron that passes between the terminals of a 12-V car battery when a 60-W headlight is on for one hour.

With Complete Solution. Thank you.

Answer 1

Given:

$V=12\:\rm V$

$P=60\:\rm W$

$t=3600\:\rm s$

The work done by electric field is given by

$$W=qV=Pt$$

The charge that passes between the terminals of a battery

$$q=\frac{Pt}{V}=\frac{60*3600}{12}=18000 \: \rm C$$

Hence, the number of particles

$$n=\frac{q}{e}=\frac{1.8*10^4}{1.6*10^{-19}}=1.125*10^{23}$$