A solenoid has 2000 turns would over a length of 0.30 m. The area of its cross-section is `1.2xx10^(-2)m^(2)`. If an initial current of 2 A in the solenoid is reversed in 0.25 s, then the emf induced in the coil is

Options

A. `6xx10^(-4)V`
B. `4.8xx10^(-3)V`
C. `6xx10^(-2)V`
D. `32.1xx10^(-2)V`

Answer

D

Explanation

Induced emf, `e=(Li)/(dt)=(mu_(0)N^(2)S)/(l)(di)/(dt)`
`=(4pixx10^(-7)xx(2000)^(2)xx1.2xx10^(-3))/(0.30)xx((4)/(0.25))=32.1xx10^(-2)V`