# Charge It! Charges and Magnets

## Example 3: Electrons in a Coulomb? 

**The Question:** 

Okay. So a Coulomb creates a lot of force. Just how much electricity is there in an electron? Or a proton? That is, what is the charge of an electron in Coulombs and how many electrons are there in a single Coulomb?

**The Answer:**

The elementary unit of charge is the magnitude of the charge of an electron which is identical to that of a proton...they only differ by their sign. A proton is positive and an electron is negative. That elementary unit is called $e$ and we’ll make considerable use of it later. For now,

$$
e=1.6 \times 10^{-19} \text{ C} \nonumber
$$

Not very much. So now the number of electrons?

$$
\begin{align*}
\text{number of electrons in 1 C}&=\frac{1 \text{ electron}}{1.6 \times 10^{-19}  
\text{ C}}=6.25 \times 10^{18} \text {electrons} \nonumber  \\
&= 6,250,000,000,000,000,000 \nonumber \end{align*}
$$

which is rather a lot.