millirad
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It takes 10 teslas to levitate a frog. I wonder how many teslas it takes to levitate a human?....................
so, it's discretely easy to float a small frog in a magnetic field from 10 to 15 Tesla inside a small space like that Bitter coil (and, if i recall correctly, that thing was still using some MW of energy and a lot of watercooling ), but for a mass of a human being, and considering also the necessary space around it for build a coil, you probably need to generate 500.000 to 1.000.000 Tesla, for have some effect ..... and you will end burned, fried and toasted much much before the levitation starts
^ yes, but also remember that the magnetic field decrease with the square of the distance, not linearly ..... if i recall correctly, that tube where they levitate the frog was 30 or 35 mm diameter, for have like 15 or 16 Tesla in the center ..... and, ofcourse, the mass of the frog was few grams, maybe 3 or 4 grams.
Also, as you've said, the magnetic field gives a force per unit of mass, but is also true that for levitate an object you need to balance the gravitational acceleration with an equal amount of force, and as you probably know, you need to use different force for lift a few grams and for lift, say, 90 Kg, cause if the gravitational acceleration is a constant, the mass of the levitating object change with his weight, so, more it weight (and more it have mass), more magnetic field you need for balance G attraction with the applied force.
Then first you need a magnetic field strong enough for lift the mass of a human body (assume a 90Kg mass for a medium human body weight), so the original magnetic field must be multiplied for that factor (just saying it empirically, say 4Tesla for each gram, you need 360.000 Tesla, for levitate a 90 Kg human body diamagnetically ..... then you need a tube where a human body can stand inside, and this means the coil must be much more large, so need to generate much more magnetic field (considering the strenght decrease with the square of the distance), for have this intensity in the equilibrium point of the coil assembly ..... i see, my estimation was also too much optimistic, you can need much more than 1.000.000 of Tesla, at the end.
Gravity scales linear with mass, but so does the magnetic force. As Benm stated, put two frogs in (double the mass), and both still levitate in the same field because on both frogs is acting the same force, proportional to the magnetic field. One frog does not suck up the field for the other.