Chapter 14, Problem 53P

For the circuit shown below, $\epsilon =20V$ , L = 4.0 mH, and R = 5.0 $\Omega$. After steady state is reached with S₁ closed and S₂ open, S₂ is closed and immediately thereafter (at t = 0) S₁ is opened. Determine (a) the current through L at t = 0, (b) the current through L at r = 4.0 x 10^-4 s, and (c) the voltages across L and R at t = 4.0 x 10^-4 s.