How effective is AC compared to DC?

The statement that AC is 70.7% as effective as DC refers to the context of power transmission and the root mean square (RMS) values associated with alternating current (AC). In both AC and DC circuits, the effectiveness of the current can be measured in terms of power delivery.

When comparing AC to DC, the effectiveness can be evaluated using the RMS value. For AC, the RMS value offers a standard by which the effective voltage or current can be expressed. The 70.7% figure stems from the relationship between peak voltage (or current) and the RMS value in sinusoidal AC waveforms, where the RMS value is approximately 0.707 of the peak value. This means that while AC is capable of delivering power through alternating voltages and currents, its effectiveness in achieving the same power delivery as DC must consider these RMS values. Thus, the calculation shows that AC has a proportional effectiveness of about 70.7% when compared to its peak values, which can inform decisions about which type of current to use in particular applications.