Question

A current of 0.92 a flows in a wire. how many electrons are flowing past any point in the wire per second? the charge on one electron is 1.60 ✕ 10-19
c.

Answer 1

The current is defined as the ratio between the charge Q flowing through a certain point of a wire and the time interval, $\Delta t$:
$I= \frac{Q}{\Delta t}$
First we need to find the net charge flowing at a certain point of the wire in one second, $\Delta t=1.0 s$. Using I=0.92 A and re-arranging the previous equation, we find
$Q=I \Delta t= (0.92 A)(1.0 s)=0.92 C$

Now we know that each electron carries a charge of $e=1.6 \cdot 10^{-19} C$, so if we divide the charge Q flowing in the wire by the charge of one electron, we find the number of electron flowing in one second:
$N= \frac{Q}{q} = \frac{0.92 C}{1.6 \cdot 10^{-19} C}=5.75 \cdot 10^{18}$