Chapter-7|Alternating Current |NCERT 12th Physics:
Mean or Average Value of AC:
It is defined as the value of AC, which would send same amount of charge through a circuit in half cycle that is send by steady current(DC) in the same time (i.e T/2) through the same circuit.
Note: We cannot calculate average value of full cycle, because it will be zero. So we will calculate average value for half cycle.
Derivation: The AC changes continuously with time. Let current is kept constant for small time dt. If dq be the small amount of charge in small time dt, then from q= It