How Is Thermal Energy Calculated in an Inductor?

[cmalle09]

An inductor used in a DC power supply has an inductance of 13H and a resistance of 160 ohms. It carries a current of 0.4 A. What is the stored energy in the magnetic field? At what rate is thermal energy developed in the inductor?

L=13H
R=160 ohms
I=0.4A

W = 1/2Li^2 = 1/2(13)(0.4)^2 = 1.04 J

I am unsure where to go from here. I can calculate the stored energy, but what do I do for the rate of thermal energy?

 

[berkeman]

Your answer for the stored magnetic energy looks correct. Now, the thermal energy dissipated actually has very little to do with the stored magnetic energy in this DC question. Think of the thermal losses as "Ohmic losses". Does that hint help?