Question

If a metal wire carries a current of 0.10 A, how long does it take for 5.00x1018 electrons to pass a given cross-

sectional area of the wire? (The charge on one electron is 1.6x10-19 C.)

Answer 1

8 seconds

Step-by-step explanation:

The current in a wire is defined as

`I=(q)/(t)`

where

q is the charge passing through a given point of the wire in a time t

In a metal wire, the current is generally carried by electrons. So, the charge passing through a certain point of the wire can be written as

`q=Ne`

where

N is the number of electrons

`e=1.6\cdot 10^(-19)C` is the fundamental charge (the charge of one electron)

So the formula becomes

`I=(Ne)/(t)`

In this metal wire we have

I = 0.10 A is the current in the wire

`N=5.00\cdot 10^(18)` is the number of electrons

Solving for the time, we find:

`t=(Ne)/(I)=((5.00\cdot 10^(18))(1.6\cdot 10^(-19)))/(0.10)=8 s`