Past exam of the physics 2 paper of the University of Oxford / 2018 / 9 / iii / Solution

For an inductor, $V=Ld{I}_L/dt$. In the steady AC solution with no added constant electric current,The electric current lags the voltage by $\pi /2$. An ideal inductor can also sustain an arbitrary DC current, fixed by initial conditions; it is excluded from this steady sinusoidal comparison.