Charge

Coulomb's law

fold/unfold

$$ \begin{flalign*} \vec{F_e} = k_e\frac{q_1q_2}{r^2}\hat{r} && \end{flalign*} $$
$$ \begin{flalign*} k_e = \frac{1}{4\pi\epsilon_0} && \end{flalign*} $$

Property of charge

First, charge is quantized. It means that charge has discrete value. Also, we can indicate this sentence as follows. $$ \begin{flalign*} q = ne && \end{flalign*} $$ Where, n is integer which is not zero, and e is elementary charge.

Second, charge is conversed. There is three examples -radioactive decay, pair annihilation, pair production-.