Question

We have seen that a coulomb is an enormous amount of charge; it is virtually impossible to place a charge of 1 C on an object. Yet, a current of $\mathbf{10}\mathbf{}\mathbf{A}\mathbf{,}\mathbf{}\mathbf{10}\mathbf{}\mathbf{C}\mathbf{/}\mathbf{s}$is quite reasonable. Explain this apparent discrepancy.

Short answer

Current is the amount of charge flowing through a specified area, per unit of time.

So, it can be a very large amount of charge carriers with a very small charge that flows. Also, it can mean that a very small amount of charge flows through a specific area in a very short time.

Step-by-step solution

Definition.

Current is the amount of charge flowing through a specified area per unit time.

Explaining the apparent discrepancy.

This does not mean that it should be only one charge of 1 C flowing in one second.

It can be very large amount of charge carriers with a very small charge that flow.

This can be shown by equation 25.2, which is given by

$I=n\left|q\right|v_{d}A$

Where, is the concentration of the charge carriers with charge $q$.

And in example 25.1, the free electron density in the wire is $8.5\times {10}^{28}{m}^{-3}$.

This amount of charge carriers are moving at a high speed $v_d$,so it can cover a length of a wire in a very short time.

Also, it can mean that a very small charge flows through a specific area in a very short time.