I knew the text book says the inductor store energy in magnetic field. The typical way they demonstrate this is by setting up a circuit, where a battery is parallel connected to a light bulb and an inductor. At the beginning, the light bulb lights up. Then the battery is cut off and the light bulb doesn't instantly turned off but slowly dimming until it is completely die out. This experiment shows that the inductor store energy. Okay I am fine with this demonstration and I also agree inductor store energy. But, can inductor store energy like a battery does? I think is better if I can illustrate a situation as follow: Now, imagine you connect only an inductor to a battery. So now the inductor slowly build up its magnetic field until the current flow reaches maximum value. Then suddenly, you take away the inductor (completely isolating it, i.e. the two terminals not connect with anything), put it at somewhere else, keep it like that for some duration (few seconds, minutes, hours, days, etc). After that, you take that inductor, connect the terminals to a light bulb, will the light bulb emits light?