`20Omega` resistance is connected to V = 220sin (100`pi`t) voltage source. Time taken by current to reduce from maximum value to its rms value is .....

Options

A. 0.2 s
B. 0.25 s
C. `25xx10^(-3)` s
D. `2.5xx10^(-3)` s

Answer

D

Explanation

`V=V_0 sin (100 pit)`
`therefore I=I_0 sin (100 pit)` Here, `delta=0`
`therefore I_0/sqrt2=I_0 sin (100pit)`
`1/sqrt2=sin (100pit)`
`therefore 100pit = pi/4`
`therefore t=1/400`=0.0025
`therefore t=2.5xx10^(-3)` s