ABSTRACT
This chapter introduces alternating current and voltages, with its terminology and values. Electricity is produced by generators at power stations and then distributed by a vast network of transmission lines to industry and for domestic use. It is easier and cheaper to generate alternating current (a.c.) than direct current (d.c.) and a.c. is more conveniently distributed than d.c. since its voltage can be readily altered using transformers. The effective value of an alternating current is that current which will produce the same heating effect as an equivalent direct current. The effective value is called the root mean square (r.m.s.) value and whenever an alternating quantity is given, it is assumed to be the r.m.s. value. If values of quantities which vary with time t are plotted to a base of time, the resulting graph is called waveform. The time taken for an alternating quantity to complete one cycle is called the period or the periodic time T of the waveform.
