Page 282 - Basic Electrical Engineering

Figure 3.5 RMS value of an alternating current illustrated

Equating expressions (3.3) and (3.4),

or,

Thus, the effective value is equal to the square root of the mean of the
squares of instantaneous values of the alternating quantities. Alternately, this

can be read as square mean root value or root mean square value, i.e., RMS
value. While expressing alternating quantities we always use RMS values and

write in capital letters as E, I, V, etc. To further clarify the concept of the