A solenoid has 2000 turns wound over a length of 0.30 metre. The area of its cross section in `1.2 times 10^-3 m^2` Around its central section, a coil of 300 turns is wound. IF an initial current of 2A in the solenoid is reversed in 0.25s, then the emf induced in the coil is:

Options

A. `6 times 10^-4V`
B. `4.8 times 10^-2V`
C. 6mV
D. 48mV

Explanation

Induced emf `E= M (dI)/(dt)= (mu_0 N_1N_2A)/l.(dl)/(dt)`
`=(4pi times 10^-7 times 2000 times 300 times 1.2 times 10^-3)/0.30 times (12-(-2)l)/0.25`
`=48.2 times 10^-3V=48mV`