Faraday's Law of Electromagnetic Induction

The quantitative relation stating that the electromotive force (emf) induced around a closed circuit equals the negative time rate of change of magnetic flux through any surface bounded by that circuit: ℰ = −dΦB/dt, where ΦB = ∫_S B·dA. Equivalently, in differential form for fields, ∇×E = −∂B/∂t.