Topic explanation

Standard explanation

AC power is the rate at which alternating electrical energy is transferred or converted.

Key points

• φ=0
• cosφ=1
• P_avg=V_rmsI_rms
• P=V_rmsI_rms cosφ
• Pure Resistance: Instantaneous power is: p=vi For a purely resistive circuit, voltage and current are in phase.
• Mean and Maximum Power: For an ideal resistive sinusoidal circuit, mean power is half the maximum instantaneous power.
• Phase difference determines how much AC power is actually transferred on average.

Labelled diagram