a. Calculate the inductance of an air core solenoid containing `300` turns if the length of the solenoid is `25.0cm` and its cross -sectional area is `4.00cm^2`.
b. Calculate the self -induced emf in the solenoid if the current through it is decreasingg at the rate of `50.0A//s`.

Explanation

a. The inductance of a solenoid is given by
`L=(mu_0N^2S)/l`
Substituting the values, we have
`L=((4pixx10^-7)(300)^2(4.00xx10^-4))/((25.0xx10^-2))H`
`=1.81xx10^-4H`
b. `e=-L(di)/(dt)`
Here `(di)/(dt)=-50.0A//s`
`:. E=-(1.81xx10^-4)(-50.0)`
`=9.5xx10^-3V`
or `e=9.05mV`