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Faraday's Law

• Magnetic flux: if a loop, of area A, sits in a uniform magnetic field B, a magnetic flux exists through the loop. If the loop plane is perpendicular to B, the flux is equal to BA. If the normal to the plane of the loop makes an angle theta with B, then the flux is given by BAcos(theta).
• Faraday’s law: If the magnetic flux through a loop changes with time, an emf is induced in the loop. The value of the emf is minus the rate of change of the magnetic flux.
• Lenz’s law: this law determines the direction of the current induced in a loop due to the changing magnetic flux. It states that the induced current has a direction so as to oppose the change of flux that induces the current. For example, if B is in the positive z direction and is increasing with time, and the loop is in the x-y plane, then the induced current will be clockwise, so as to produce a magnetic field in the negative z direction.