How does distance affect magnetism?

Answer 1

Magnetic field strength (H) is defined as the magnetomotive force per unit length, and is expressed in amperes per metre (often spoken as 'ampere turns per metre') in SI. An older, and far more descriptive term, is 'magnetomotive force gradient'.

The 'closeness' or intensity of a magnetic field's flux lines, on the other hand is termed magnetic flux density(B), expressed in teslas in SI.

There is a complex relationship between magnetic field strength and flux density, because of a property exhibited by ferromagnetic materials, called 'hysteresis'. In general, as the magnetic field strength applied to a sample of unmagnetised ferromagnetic material increases, the resulting flux density also increases (but not linearly) until saturation is reached, at which point any further increase in magnetic field strength will have no effect whatsoever on the flux density. If the magnetic field strength is then reduced, the flux density will also reduce (again, not linearly), but when the magnetic field strength reaches zero amperes, a certain amount of flux density remains.

So to answer your question, you really need to study what's known as the B-H or magnetising curve for a sample of ferromagnetic material -this will show you exactly what the relationship between magnetic field strength and flux density for any give ferromagnetic material.

Answer 2

Magnetic force is inversely proportional to the square of the distance from the magnet which generates it.

Answer 3

the greater the distance, the lower the magnetic effect, and vice versa.

Answer 4

A