I understand the very basics about it. I know it basically resists changes in current. However, in a circuit that is powered by a 12V DC battery why in the heck would we need an inductor (to filter tiny fluxuations in a DC power supply possibly)? My thought (and maybe I am totally wrong) is that an inductor would only be useful in AC circuits. But I am just not seeing its purpose in a DC application?

The particular inductor I am working with is 100uH. Again, I understand this is basically the measure of inductance, but if I am applying 12V DC then after the magnetic field is established I should expect 12V DC coming out correct?

Alternatively lets say for example I were to plug an inductor of some size into the wall 120V AC coming into an inductor, what would we expect to come out? That's where I am lost, would we get 120V DC out?

Thanks in advance for any help understanding this...