7.8 : 功率叠加原理

Consider a circuit with two sinusoidal voltage sources.

According to the superposition principle, the total current resulting from both sources is the sum of currents due to each source independently.

Also, the instantaneous power is the square of the instantaneous current times the resistance.

Integrating this over one period yields the average power, which equals the sum of average powers due to each source, and a third term—that equals zero for sources having different frequencies.

The simplified equation signifies the power superposition principle, stating that the average power delivered by sources having different frequencies equals the sum of the average power delivered by each source.

This principle is crucial in telecommunications, such as radio broadcasting.

Multiple radio stations broadcast their signals simultaneously, each acting as an independent source of electromagnetic waves.

According to the power superposition principle, the total power received by the radio is the sum of powers transmitted by each station.

Tuning the radio to a specific frequency allows the user to listen to one station at a time, despite receiving signals from multiple stations.