Induced EMF

An EMF doesn’t have to be created through a chemical reaction. It can be induced through Electromagnetic Induction. This is explained through the concept of Magnetic Flux, and the fact that an induced EMF is caused by a change in magnetic flux (and not just magnetic field).

The strength of the EMF induced is given by Faraday’s Law of Induction

Recall that magnetic flux is given by:

A change in Magnetic Flux induces an EMF. This change can occur in two ways:

• Motional EMF: Change in area intersecting a Magnetic Field, resulting in EMF. This can occur by either moving the conductor in the field, or rotating it
• Static-Induced EMF: Changing the strength/direction of the Magnetic Field - This isn’t motional EMF, as the conductor isn’t moving. However, Faraday’s Law of Induction states that there is still an EMF induced. It actually occurs due to Induced Electric Fields

Expanding Faraday’s Law of Induction §

Faraday’s law of induction is given by:

We can expand the change in magnetic flux:#todo how exactly does this work?

$$|\mathcal{E}|=|\frac{\text{d}{\Phi }_B}{\text{d}t}|=\left|\vec{B}\cdot \frac{\text{d}\vec{A}}{\text{d}t}+\vec{A}\cdot \frac{\text{d}\vec{B}}{\text{d}t}\right|$$

• $\vec{B}\cdot \frac{\text{d}\vec{A}}{\text{d}t}$ = Motional EMF
• $\vec{A}\cdot \frac{\text{d}\vec{B}}{\text{d}t}$ = Static-Induced EMF