phill said:
The specalist told me the elctro magnets they use in them machines are stronger than the earths gravitational pull!
that doesn't make any sense.
magnets have a magnetic field.
gravity is a gravitational force.
you can't compare one agaist the other in terms of magnitude.
unless the specialist meant to say that the magnetic field of the scanner was greater than the earths magnetic field.
which would be true but then it would also be true of even a small bar magnet.
you probably know this already anyway. you must have seen what happens to a compass when you move it close to a small magnet and it responds to the overwhelming field of the nearby magnet over the weak earth field.
though you need the numbers to get the full wow of it.
earth's magnetic field = 0.00005 Tesla
typical hospital mri scanner = 1.5 Tesla
some newer models go upto 3 Tesla. research machines go higher still.
i've played with a 7 Tesla unit.
if it's an electro magnet, it will likely be 0.5 Tesla or less, the 1.5 Tesla and above machines are superconducting. ie. they use electricity to get them upto full field but thereafter they sustain themselves through zero (or almost zero) resistance.