Why doesn't magnetic field strength decrease as a function of x in B = 1/x^2? For that matter, it does not decrease as a function of 1/x^n in any case where n would be a constant - n must be a variable! Can someone explain this to me? It does not correspond to inverse square law.. Thx!

Question

anonymous · Answer

For a long thin solenoid that approximates a magnetic  dipole (or a theoretical magnetic dipole)  the field varies as 1/x^3 with a cosine (angle between x and dipole axis) dependence.  Since all real magnets have extended crossectional areas and correspondingly shorter lengths they cannot be represented as a true dipole and therefore the x dependence is more complex.