A long solenoid of radous `R` has `n` turns of wire per unit length and carries a time-varying current that varies sinusiodally as `I = I_(max) cos omegat`, where `I_(max)` is the maximum current and `omega` I the angular frequancy of the alternating current source (shows in Fig.)

The magnitude of electric field outside the solenoid at a distance `r gt R` from its long central axis is

Options

A. `(mu_(0)nI_(max)omega R^(2))/(2r) sin omega t`
B. `(2mu_(0)nI_(max)omega R^(2))/(r) sin omega t`
C. `(mu_(0)nI_(max)omega R^(2))/(3r) sin omega t`
D. `(3mu_(0)nI_(max)omega R^(2))/(2r) sin omega t`

Answer

A

Explanation

`E = (R^(2))/(2r) (dB)/(dt) = - (R^(2))/(2r) mu_(0)nI_(max) omega sin omega t`
`= - (mu_(0)nI_(max)omega R^(2))/(2r) sin omegat`