Such a voltage is called alternating voltage (ac voltage) and
the current driven by it in a circuit is called the alternating current (ac
current)* Today, most of the electrical devices we use require ac voltage This is mainly because most of the electrical energy sold by power
companies is transmitted and distributed as alternating current The main
reason for preferring use of ac voltage over dc voltage is that ac voltages
can be easily and efficiently converted from one voltage to the other by
means of transformers