A coil of wire has an inductance of 40 mH and a resistance of 4 Ω. It is connected to a 20 V battery at the instant t = 0. Consider the moment when the current is 3 A.
a) At what rate is energy being delivered by the battery? (That is, what power is the battery providing?)
b) What is the power being delivered to the resistance of the coil?
c) At what rate is energy being stored in the magnetic field of the coil?
d) After the switch is closed for a long time, what are the values of the three powers?