The current in a coil of self-inductance `4H` is given by `i=4sint^(2)` . Find the amount of energy spent during the period when the current changes from `0` to `4A` .

Explanation

When the current in the coil is variable, small work done in time `dt`
`dW=Pdt=eidt=(L(di)/(dt))idt=Lidi`
`W=Lint_(0)^(4)idi`
`=4|(i^(2))/(2)|_(0)^(4)=32J`