Question

3. A car headlight may put out 100 W at 25 V.
a) Calculate the current drawn by the headlight.
b) How many electrons pass through the bulb filament each second?

Answer 1

a)

$$I=\frac{P}{U}=\frac{100}{25}=4\ A$$

b)

$$N=\frac{I}{e}=\frac{4}{1.6\cdot 10^{-19}}=2.5\cdot 10^{19}$$