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= (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= (Q)/(q) = (0.92 C)/(1.6 \cdot 10^(-19) C)=5.75 \cdot 10^(18)`