Formula: Electric Power Voltage Electrical Resistance
$$P ~=~ \frac{U^2}{R}$$
$$P ~=~ \frac{U^2}{R}$$
$$U ~=~ \sqrt{ P \, R }$$
$$R ~=~ \frac{U^2}{P}$$
Electric Power
$$ P $$ Unit $$ \mathrm{W} = \frac{\mathrm J}{\mathrm s} $$
Electric power is the energy emitted / absorbed by a circuit per second, for example.
Voltage
$$ U $$ Unit $$ \mathrm{V} = \frac{ \mathrm J }{ \mathrm C } = \frac{ \mathrm{kg} \, \mathrm{m}^2 }{ \mathrm{A} \, \mathrm{s}^3 } $$
Electric voltage here is the potential difference between two points. For example, between two points of an electrical conductor. If the voltage is doubled, the power converted is quadrupled.
Electrical Resistance
$$ \class{brown}{R} $$ Unit $$ \mathrm{\Omega} = \frac{ \mathrm{kg} \, \mathrm{m}^2 }{ \mathrm{A}^2 \, \mathrm{s}^3 } $$
Electrical resistance impedes the flow of electrically charged particles in a conductor. If the voltage \(U\) is kept constant, the smaller the resistance \(R\), the larger the power converted.