Formula: Plate Capacitor Electric force Electric charge Voltage Distance
$$F ~=~ \class{red}{q} \, \frac{U}{d}$$
$$F ~=~ \class{red}{q} \, \frac{U}{d}$$
$$\class{red}{q} ~=~ \frac{F_{\text{e}}}{U} \, d$$
$$U ~=~ \frac{F_{\text{e}}}{\class{red}{q}} \, d$$
$$d ~=~ \class{red}{q} \, \frac{U}{ F_{\text{e}} }$$
Electric force
$$ F $$ Unit $$ \mathrm{N} $$
Force acting on a charge \(q\) when it is placed between the two plates of the capacitor. The force occurs because the negative charge is attracted to the positive capacitor plate and repelled by the negative capacitor plate.
Electric charge
$$ q $$ Unit $$ \mathrm{C} = \mathrm{As} $$
This is the charge (e.g. from an electron or proton) placed inside the plate capacitor.
Voltage
$$ U $$ Unit $$ \mathrm{V} = \frac{ \mathrm J }{ \mathrm C } = \frac{ \mathrm{kg} \, \mathrm{m}^2 }{ \mathrm{A} \, \mathrm{s}^3 } $$
Voltage applied between the two electrically charged capacitor plates. This quantity is a measure of how large the charge difference is between the two plates.
Distance
$$ d $$ Unit $$ \mathrm{m} $$
This is the distance between the two capacitor plates (also called electrodes).