Ohm's Law
V = I × R
Relates voltage, current, and resistance in a linear resistive circuit.
Power (P = VI)
P = V × I
Electrical power delivered to a load equals voltage times current.
Power (P = I²R)
P = I² × R
Power dissipated as heat in a resistor given current and resistance.
Power (P = V²/R)
P = V² / R
Power delivered to a resistive load from voltage and resistance alone.
Electrical Energy
E = P × t
Total energy consumed equals power multiplied by time.