An air cored solenoid is of length 0.3 m, area of cross section `1.2 xx 10^(-3) m^(2)` and has 2500 turns. Around the solenoid and the coil are electrically insulated from each other. Calculate the e.m.f. induced in the coil if the initial current of 3 A in the solenoid is reversed in 0.25 s.

Explanation

Here, `l = 0.3 m, A = 1.2 xx 10^(-3) m^(2), N_(1) = 2500`
`N_(2) = 350, e = ?, dI = - 3 - (3) = - 6 A`
`dt = 0.25 s`.
`e = - M (dI)/(dt) = - (mu_(0) N_(1) N_(2) A)/(l) ((dI)/(dt))`
` = (- 4pi xx 10^(-7) xx 2500 xx 350 xx 1.2 xx 10^(-3) (-6))/(0.3 xx 0.25)`
`e = 0.106 V`