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Faraday's Law

1. Faraday's law relates electric fields to changing magnetic fields:

   ∫_{closed loop} E ⋅ ds = - dΦ_B/dt

   (= - ΔV from above; be careful with the signs here!).

   The minus sign is a result of Lenz's law: the induced current is in a direction which creates an opposing magnetic field.
2. Note that the magnetic flux can have a time dependence because
   • the magnetic field itself changes with time;
   • the area of the loop changes with time; or
   • the angle between the field and the normal to the loop changes with time.

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©2010, Kenneth R. Koehler. All Rights Reserved. This document may be freely reproduced provided that this copyright notice is included.

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