For an inductor coil, \(L = 0.04 ~\text{H}\), the work done by a source to establish a current of \(5~\text{A}\) in it is:
1.  \(0.5~\text{J}\)
2.  \(1.00~\text{J}\)
3.  \(100~\text{J}\)
4.  \(20~\text{J}\)

For a coil having \(L=2~\text{mH},\) the current flow through it is \(I=t^2e^{-t}.\) The time at which emf becomes zero is:
1. \(2\) s
2. \(1\) s
3. \(4\) s
4. \(3\) s