# How does alternating current transfer energy?

##### 1 Answer

Whenever there is current, electrons flow (the usual case). Electrons that move carry energy in terms of voltage. Suppose that we want to transfer energy to a resistor in a circuit,

The power (which is a good way to express energy) is

For a direct current, the math is simple. For alternating current with peak current **I** , the effective current becomes

Hence the Power transferred is

If you are asking about transmission of energy to households, then alternating current is needed to keep changing magnetic flux through a Gaussian surface so that electricity is continuously produced via generator and altered via transformer. Direct current is useless in power generation.