What is i4 the magnitude of the current through the

Question

A circuit is constructed with four resistors, one inductor, one battery and a switch as shown. The values for the resistors are: R₁ = R₂ = 42 Ω, R₃ = 72 Ω and R₄ = 148 Ω. The inductance is L = 206 mH and the battery voltage is V = 12 V. The positive terminal of the battery is indicated with a + sign.

1) The switch has been open for a long time when at time t = 0, the switch is closed. What is I₄(0), the magnitude of the current through the resistor R₄ just after the switch is closed?

2) What is I₄(3), the magnitude of the current through the resistor R₄ after the switch has been closed for a very long time?

3) What is I_L(3), the magnitude of the current through the inductor after the switch has been closed for a very long time?

4) After the switch has been closed for a very long time, it is then opened. What is I₃(t_open), the current through the resistor R₃ at a time t_open = 3.6 ms after the switch was opened? The positive direction for the current is indicated in the figure.

5) What is V_L,max(closed), the magnitude of the maximum voltage across the inductor during the time when the switch is closed?

6) What is V_L,max(open), the magnitude of the maximum voltage across the inductor during the time when the switch is open?