Why does an inductor cause current to lag voltage? Doesn't a conductor need to have current running through it while it is passed through a magnetic field to produce an opposing EMF?

I'm not seeing many surface-mount electromagnets out there. There are definitely a lot of SMD inductors available, and I hope they're cheap. How can I calculate the magnetic force they will exert?Btw, I'm trying to build an electromechanical display. And I'd like to have a rotating element with a magnet in it, then I'd use an el...

I think more how does a signal have both an AC and DC component? I understand that an inductor at a high frequency will have a very high impedance and thus not allow current to flow. But wouldnt that happen with DC as well ?