When current in an inductance is changed at a uniform rate from 15 A to 30 A in 3 s, the self-induced emf in the coil is 25 V. The change in energy of the coil during this process is:

Step-by-step solution

Rate of change of current: di dt = 30 - 15 3 = 5 A/s Self-induced emf: e = L di dt 25 = L 5 L = 5 H Change in energy stored in the inductor: U = 1 2 L(i_f^2 - i_i^2) = 1 2 5 (30^2 - 15^2) = 2.5 (900 - 225) = 2.5 675 = 1687.5 J