In the circuit shown below, the key K is closed at t=0. The current through the battery is
We know that,
At t=0, inductor behave like an infinite resistance
So, at t=0
i=VR2
Now, at t=∞, inductor behave like conductive wire
So,
i=V(R1+R2)R1R2
Hence, the current is i=VR2 at t=0 and V(R1+R2)R1R2 at t=∞