Needing help with RL transients

Thread Starter


Joined Apr 6, 2011
I am looking for help with a question I have regarding working out the current in a circuit I have been given, the problem comes where my tutor will not be around for a while so I am stuck for which equations to use but here is the question below with the circuit diagram.

Work out the current through R4 and through R5&L3...
- As soon as the switch is closed
- After the switch has been closed for a long time (5time constant)
- As soon as the switch is opened
- 400nS after the switch is opened

I have worked out my time constants to be 6.833uS (charging) and 872.340nS (discharging). I also think I may have worked out the current when the switch is first closed to be 7.31mA for R4 and 0A for R5&L3.