Question

The expression for energy of an inductor ____________

(a) ½ LI

(b) L/2I

(c) ½ L^2I

(d) ½ LI^2

This question was posed to me in an international level competition.

Origin of the question is Inductor and Capacitor in section Inductance, Capacitance, and Mutual Inductance of Electric Circuits

Answer 1

The correct answer is (d) ½ LI^2

Best explanation: E=∫p dt

            =∫ LI*(dI/dt).dt

            = L∫I dI

            = ½ LI^2.