$ \nabla \times \mathbf {E} =-{\frac {\partial \mathbf {B} }{\partial t}}$
This law explains how changing magnetic fields create electric fields. When a magnetic field changes over time, it generates an electric field around it. This phenomenon is used in generators and transformers.
The curl ∇ × of the electric field E equals the negative of the partial derivative of the magnetic field B with respect to time t
Integral form: $\displaystyle \oint _{\partial \Sigma }\mathbf {E} \cdot \mathrm {d} \mathbf {l} =-\int _{\Sigma }{\frac {\partial \mathbf {B} }{\partial t}}\cdot \mathrm {d} \mathbf {A}$