Engineering Reversing Current in Part F: Seeking Help

[Foilist]

The attached document contains the question and the answers I have calculated. I am confident that I have answered them correctly however another pair of eyes is always useful.


The problem I have is with part f - Rate of change of current at the instant the switch is closed on position 2. I know that the current needs to reverse, and that the inductor will oppose this reversal, until such time as eventually the steady-state current calculated at part d will be reached, however I'm at a loss as to where to start the calculations.

 

[CEL]

You have an expression for the current at every instant t 0<t<0.72s.
If you differentiate that expression you have di/dt. Replace t by 0.72 and you have the rate of change at that instant.
Replace t by 0 and check the result you obtained in item e.