ABSTRACT
The r.m.s. value of voltage V = 0.707Vm , i.e. V =Vm/√2, from which, Vm =√2 V . Similarly, the r.m.s. value of current, I = Im /√2, from which, Im =√2 I . Hence the average power, P, developed in a purely resistive a.c. circuit is given by
P = 12 Vm Im = 12 ( √
2 V )( √
2 I )=VI watts Also, power P = I 2 R or V 2/R as for a d.c. circuit, since V = IR.
