Question

A total of 2.0x 1013 electrons pass a given point in a wire in 15s. what is the current in the wire

Answer 1

The current in a wire is defined as the amount of charge that passes a given point of the wire in a given time:

`I= (Q)/(\Delta t)`
where Q is the charge and
`\Delta t` is the time interval.

Since one electron has a charge of
`q=1.6 \cdot 10^(-19)C`, the total charge of
`2.0 \cdot 10^(13)` electrons is

`Q=qN=(1.6 \cdot 10^(-19) C)(2.0 \cdot 10^(13) )=3.2 \cdot 10^(-6) C`

And since the time interval is
`\Delta t=15 s`, the current in the wire is

`I= (Q)/(\Delta t)= (3.2 \cdot 10^(-6) C)/(15 s)=2.1 \cdot 10^(-7)A`