Power Dissipation (I²R Losses)
When current flows through a resistive component, electrical energy is converted to heat. This power dissipation is given by Joule’s law: P = I2R, where I is the current through the component and R is its resistance.
This relationship shows that power dissipation grows with the square of current, so even a modest increase in current causes a much larger increase in heat generated — a key reason electrical systems use higher voltages (and correspondingly lower currents) to transmit the same power over long distances with less resistive loss. This formula is equivalent to P = V²/R and P = VI via Ohm’s law.
Last reviewed August 2026