Lenz's Law
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Lenz's Law is a law which was published in 1833 by Emil Lenz. It determines the direction of the electric current in electromagnetic induction. The law says:
| “ | The induced current is always directed such that it always acts contrary to its cause. | ” |
It is necessary for there to be conservation of energy. It comes from the fact that the induced current produces a magnetic field in addition to the one that caused the induced current. Faraday's law describes induction mathematically relating the voltage induced, V, to the magnetic flux, ΦB , as:
<math> V = \frac{d \phi_B}{dt} </math>
The minus sign represents Lenz's law, that the induced voltage (and therefore current that might flow) will oppose the flux that is causing it.