how to calculate magnetic pole strength?

Magnetic field strength, in gauss, can be calculated at any distance from the end of a magnet.Devices used to measure the local magnetic field are calledmagnetometers. Important classes of magnetometers include using a rotating coil,Hall effectmagnetometers,NMR magnetometers,SQUID magnetometers, andfluxgate magnetometers. The magnetic fields of distantastronomical objectsare measured through their effects on local charged particles. For instance, electrons spiraling around a field line producesynchrotron radiationthat is detectable inradio waves.