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This basic law of Electromagnetic Induction, derived by the genius of the great English chemist and physicist Michael Faraday (1791–1867), presents itself in two different forms:

1 A moving conductor cutting the lines of force (flux) of a constant magnetic field has a voltage induced in it.

2 A changing magnetic flux inside a loop made from a conductor material will induce a voltage in the loop.

In both instances, the rate of change of the magnetic field is the critical determinant of the resulting voltage potential. Figure 1.5-1 illustrates both cases of electromagnetic induction and also provides the basic relationship between the changing flux and the voltage induced in the loop. The first case shows the relationship between the induced voltage in a wire moving across a constant field. The second case shows one of the simple rules that can be used to determine the direction of the induced voltage in the moving conductor.

Figure 1.5-1 Both forms of Faraday's basic law of electromagnetic induction. A simple rule (the “right‐hand” rule) is used to determine the direction of the induced voltage in a conductor moving across a magnetic field at a given velocity.