A `50cm` long solenoid having `500` turns and radius `2cm` is wound on an iron core of relative permeability `800` . What will be the average emf induced in the solenoid if the current in it changes from `0` to `2A` in `0.05` sec?

Explanation

For solenoid
`L=(mu_(0)mu_(r)N^(2)pir^(2))/(l)`
`=((4pixx10^(-7))(800)(500)^(2)pi(0.02)^(2))/(0.5)`
`=0.64H`
`bar(e)=-L(Deltai)/(Deltat)=-(0.64(2-0))/(0.05)=25.6V`