The time taken by A.C. voltage of frequency 50 Hz to change from zero to maximum is ……. ms.

Options

A. 5
B. 10
C. 20
D. 50

Answer

A

Explanation

`V=V_m sin omegat`
If `V=V_m` then 1 = sin `omegat`
`therefore omegat=pi/2`
`therefore t=(pixxT)/(2xx2pi) [because omega=(2pi)/T]`
`therefore t=T/4`
`therefore t=1/(50xx4) [ because T=1/f = 1/50]`
`therefore t=1/200`
`therefore t=5xx10^(-3)` s
`therefore` t=5 ms