Faraday's law of induction is a law of physics proposed by English physicist Michael Faraday in 1831.[1] It is one of the basic laws of electromagnetism. The law explains the operation principles of generators, transformers and electrical motors.

Faraday's law of induction says that when a magnetic field changes, it causes a voltage.[2] That phenomenon was also found by Joseph Henry in 1831.[3] To describe the law, the magnetic flux and also a surface with a wire loop as border is considered. This leads to the following surface integral:

${\displaystyle \Phi _{B}=\iint \limits _{\Sigma (t)}\mathbf {B} (\mathbf {r} ,t)\cdot d\mathbf {A} }$

When the flux changes, it produces electromotive force. The flux changes when B changes or when the wire loop is moved or deformed, or when both happens. The electromotive force can then be calculated with the following equation:

${\displaystyle {\mathcal {E}}=-N{{d\Phi _{B}} \over dt}}$
• ${\displaystyle {\mathcal {E}}}$ is the electromotive force
• N is the number of loops the wire makes
• ΦB is the magnetic flux of one loop

References

1. "Faraday's Law of Induction > ENGINEERING.com". engineering.com. 2012 [last update]. Retrieved 6 August 2012. Check date values in: |date= (help)
2. "Faraday's Law". hyperphysics.phy-astr.gsu.edu. 2004 [last update]. Retrieved 6 August 2012. Check date values in: |date= (help)
3. "Joseph Henry". nas.edu. 2012 [last update]. Retrieved 6 August 2012. Check date values in: |date= (help)