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Ohm's Law defines the relationship between power, voltage, current, and resistance. The various possible formulas for Ohm's law are as follows.

Where
P = power in watts
E = voltage in volts
I = current in amps
R = resistance in ohms

P = E²/R
P = I² * R
P = E * I

E = sqrt(P * R)
E = P/I
E = I * R

I = E/R
I = P/E
I = sqrt(P/R)

R = E/I
R = E²/P
R = P/I²