A resistance of 20 ohms is connected to a source of an alternating potential V=220 sin(100 πt). The time taken by the current to change from its peak value to r.m.s value is
Resistance = 20 ohm
Voltage = V=220 sin(100 πt)
Step 2, Finding the time
Peak value to r.m.s. value means, current becomes 1√2 times.
From the question
V=220sin100πt
So, we can write
i=i0sin100πt
Now,
1√2×i0=i0sin100πt
Or, sinπ4=sin100πt
Or, t=1400 sec=2.5×10−3 sec
Hence, option (C) is correct