What are the Units and Instruments for Measuring Magnetic Fields?

[Jonh Doe]

I would like to know what is(are) the unit(s) of measurement for the magnetic fields of permanent magnets, and what is the instruments for measuring it (if one exists). Thirdly, is there a way to calculate such a field (mathemeticaly, by measurements, etc...)

I have heard of many things (ampere-meters, volt-tour, etc...), but I can't seem to be able to see clearly in all of them.

Thank you for your answers

 

[Cyclotron Boy]

Magnetic Fields

Magnetic fields are measured in terms Teslas and Gauss. 1 Tesla = 10000 Gauss. Permanent magnets get their magnetism from the alignment of magnetic domains within the material of the permanent magnet. Each magnetic domain acts like a little bar magnet. Aligning all the little bar magnets within the material creates a strong magnet. Most permanent magnets are characterized by their field strength at the surface of the magnet. This is typically measured with a Hall effect probe or other magnetometer. One simple method is with a flip-coil magnetometer. Those are described in most every undergraduate physics textbook.

Good luck!

 

[Chen]

At class we measured the magnetic field B of a given magnet by measuring the force on a wire with current.

F_m = IBl

When:
I = \mbox{ current in the wire }
B = \mbox{ magnetic field intensity nearby the wire }
F_m = \mbox{ length of the wire }