What do you mean ^3 or ^5? Is there some funky physics I'm misunderstanding here?
Because magnets have two poles, the force drops off by varying amounts, depending on the shape and size of the magnet. (The closer pole attracts, while the farther one repels. The other magnet also has two poles, which makes things even more complicated. For example in a short magnet the second pole has a greater influence than it does in a long one.)
It also depends on if you are interacting with another magnet, or with unmagnetized iron. ^3 or ^5 is just an approximation - it can go to ^7, and it's not a definite number, it varies.
See: http://www.exo.net/~pauld/activities/magnetism/forcebetweenm...
>> The field doesn't encompass the whole room or anything.
>Well, technically it encompasses the entire universe - or least the part that is in the light cone since the field was energized. :)
As permittivity is generally a function of frequency doesn't this mean that the progress of a magnetic field through space can differ to that of a [theoretical] light cone (which bounds the volume of causal connectedness)?
Magnetism gives me headaches.
Well, technically it encompasses the entire universe - or least the part that is in the light cone since the field was energized. :)
But magnetic fields drop off by distance^3 or ^5, so the strength drops rapidly with distance.