State Faraday's law of electromagnetic induction.

Explanation

Statement : The magnitude of the induced emf in a circuit is equal to the time rate of change of magnetic flux through the circuit.
Explanation : If change in magnetic flux is `dphi` in dt seconds then, according to Farday.s law of electro-magnetic induction.
Induced emf, ` epsi prop (dphi_B)/(dt) `
`epsi = - (dphi_B)/(dt)`
The negative sign indicates that the induced emf always opposes any change in magnetic flux associated with the circuit.