Question

How many electrons pass through a conductor in 3 milliseconds if the current is 5mA?

Answer 1

Let's first find the total charge that flows through the conductor in 3 milliseconds:

$$Q=It=5\cdot10^{-3}\ A\cdot3\cdot10^{-3}\ s=15\cdot10^{-6}\ C.$$

Finally, we can find the number of the electrons that pass through the conductor in 3 milliseconds:

$$Q=Ne,$$ $$N=\dfrac{Q}{e}=\dfrac{15\cdot10^{-6}\ C}{1.6\cdot10^{-19}\ C}=9.37\cdot10^{13}\ electrons.$$