Physics

Ben Franklin discovered that all objects have electric "fluid"; some with excess, some with deficiency.

But didn't know about electrons - 50% chance of getting positive/negative right, but got it wrong.

glass - silk : positive charge

rubber - fur : negative

F = \frac{q_1 q_2 K}{r^2} \hat{r}_{1,2}

q_p = - q_e = 1.6 \times 10^{-19} C

K = 9 \times 10^9 N m^2 C^-2 = \frac{1}{4 \pi \epsilon_0}

Electricity is 10^{36} times stronger than gravity.

But large objects are typically neutral, so gravity dominates at large scales.