Faraday's Law of Electromagnetic Induction states that the magnitude of the electromotive force (EMF) induced in a circuit is directly proportional to the time rate of change of the magnetic flux (${\Phi }_B$) through the circuit. $|E|=\left|\frac{d{\Phi }_B}{dt}\right|$

• Magnetic flux ${\Phi }_B=\vec{B}\cdot \vec{A}=BA\cos \theta$.
• Changing $B$, $A$, or the orientation $\theta$ will induce an EMF.