Flux and Faraday's law

Flux (F) is defined as the product of field strength, B, and area perpendicular to the field, A. If the field is uniform the flux through a loop perpendicular too the field is just BA. The flux through a loop can be changed in several ways.

• Change the field strength.
• Rotate the loop(s).
• Distort the loop(s).

Faraday's law

When a conductor moves in a magnetic field the induced voltage E is given by the rate of change of flux.

The negative sign is inserted by some authors to remind us that the direction of the induced voltage is such that if a current flows the magnetic field generated is in a direction to oppose the change in flux.

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