Magnetic field strength (B)

A force acts on a wire carrying a current at right angles to both the wire and a magnetic field. The size of this force is given by.... f = BIL ... where I is the current in Amps, L is the length of the wire in meters, and B is a constant. The definition of magnetic field strength B, follows at once from the force equation.

The unit of B is the Newton per Amp meter which is called the Tesla. The field of the Earth in a horizontal direction at sea level near the equator is around....

The field close to a strong permanent magnet is about one Tesla. The maximum field strength of a rare-earth alloy permanent magnet is around 5 T. Superconducting magnetic coils with many thousands of turns can generate about 10 T. Higher fields can be created for short times by imploding a container with dynamite.

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