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Electricity and Magnetism
Measuring the Strength of a Magnetic Field
When current flows through a conductor which is in a magnetic field, the conductor experiences a force (unless the current flows parallel to the magnetic field).
Factors affecting the Magnitude of the force
Experiments show that:
and, if the current flows at 90° to the field, the constant is called the magnetic flux density (symbol, B).
Flux density is the force per unit current per unit length acting on a conductor placed at 90° to the field.
If the conductor is placed at an angle to the field, then the force is given by: