Magnetic Strength

[Nim]

How powerful would a magnet's magnetic field have to be to move something as big as a typical car towards it from, say 50 feet away?

And how powerful would it have to be to be hazardous to someone? Would the first problem arise from it attracting the iron in your body?

[Adrian Baker]

Depends what you mean by 'powerful'. Your question is a little un-scientific. What units do you want the answer in? To answer in non-physics terms, VERY powerful. Go to a car scrapyard and have a look - they have them there.

No, they wont do you any damage. At least non that I know of. Strong fields are used in MRI scanning without any side affects.

[Nim]

I was thinking in terms of gauss or tesla. I am pretty sure 20,000 gauss can pull a paper clip across the room.

A magnetic field above 1e9 ( 1 billion) gauss squeezes electron orbitals into cigar shapes, which would instantly kill a human. In a 1e14 gauss field, a hydrogen atom becomes 200 times narrower. Magnetars, which have the largest magnetic fields known in the universe, are about 1e15 or 1e16 gauss.

[pallidin]

Those are some very interesting statistics, NIM.
Magnetic research, in my opinion, is a science worthy of serious endeavor, given the astounding effects at high field strenghts.
Research and development has always been somewhat problematic, but the goal is clear: high-density flux.