A resistance of 20Ω is connected to a source of an alternating potentialV=220 sin100πt . The time taken by the current to change from the peak value to rms value, is

Both V and I are in the same phase. So, let us calculate the time taken by the voltage to change from peak value to rms value. Now 220=220 sin100πt1or 100πt1=π2 or t1=1200sAgain, 2202=220 sin 100πt1or 12=sin 100πt2  or  100πt2=3π4or  t2=3400sRequired time =t2-t1=1400s=2.5×10-3s