**Alternating Current – Notes**

**Ac voltage applied to a resistor**A time-varying voltage that varies like a sine function is called AC voltage.

The current driven by an AC voltage is called AC current.

AC is preferred to DC mainly because AC voltages can be easily and efficiently converted from lower to higher voltages and vice versa using transformers.

In a pure resistor, the current flowing through the resistor is in phase with the potential difference across it.

The ratio of the instantaneous voltage and instantaneous current in a resistor is constant.

**AC voltage applied to an inductor**

An inductor is an electrical component that can store energy in the magnetic field created by a varying current flowing through it.

Any change in current through an inductor induces an emf across it, which is proportional to the rate of change of current.

The power supplied to an inductor on an average in an AC circuit over one complete cycle is zero.