The rms value of an ac of 50Hz is 10A. The time taken by an alternating current in reaching from zero to maximum value and the peak value will be

Options

A. `2 xx 10^(-2)` sec and 14.14 amp
B. `1 xx 10^(-2)` sec and 7.07 amp
C. `5 xx 10^(-3)` sec and 7.07 amp
D. `5 xx 10^(-3)` sec and 14.14 amp

Answer

D

Explanation

`l_("rms") = 10 A implies l_(o) = 10sqrt(2) A = 14.14` Amp
Let `I = 0` when `t = 0`.
`:. l = l_(o) sin omega t`
`l_(o) = l_(o) sin omega t implies omega t = (pi)/(2)`
`implies t = (pi)/(2 omega) = (pi)/(2 xx 2pi xx f) = (1)/(200) = 5 xx 10^(-3) sec`