linguistic:translation
Electromagnetic induction of conducting loop spinning in magnetic field

The magnetic flux through a loop of area A whose normal is at an angle θ to a magnetic field of strength B is

Faraday's law of electromagnetic induction states that the induced electromotive force E {\displaystyle {\mathcal {E}}} is the negative rate of change of magnetic flux Φ B {\displaystyle \Phi _{B}} through a conducting loop.

If the loop area A and magnetic field B are held constant, but the loop is rotated so that the angle θ is a known function of time, the rate of change of θ can be related to the rate of change of Φ B {\displaystyle \Phi _{B}} (and therefore the electromotive force) by taking the time derivative of the flux relation

If for example, the loop is rotating at a constant angular velocity ω, so that θ = ωt, then