Lenz's law

Lenz's law (pronounced /ˈlɛnts/), named after the physicist Heinrich Lenz who formulated it in 1834, says:

The direction of current induced in a conductor by a changing magnetic field due to Faraday's law of induction will be such that it will create a field that opposes the change that produced it.

Lenz's law is shown by the negative sign in Faraday's law of induction:

which indicates that the induced voltage (${\displaystyle {\mathcal {E}}}$) and the change in magnetic flux (${\displaystyle \partial \Phi }$) have opposite signs. It is a qualitative law that specifies the direction of induced current but says nothing about its magnitude. Lenz's Law explains the direction of many effects in electromagnetism, such as the direction of voltage induced in an inductor or wire loop by a changing current, or why eddy currents exert a drag force on moving objects in a magnetic field.

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