The study of electromagnetic induction is based on two independent discoveries by Michael Faraday and Joseph Henry.
Before I get into it, I'll explain three crucial terms which will be used in this post.
Electromotive force (EMF) is the same force generated by batteries, also known as voltage. EMF causes electrons to move around in a closed electric circuit.
Magnetic flux is the measure of how much magnetic field passes through a closed electric circuit.
Inductors are electrical components made of coils. These coils contain a magnetic field that opposes voltage change.
Faraday stated that EMF is generated whenever a closed electrical circuit experiences a change in magnetic flux. He also stated that the EMF generated is directly proportional to the change in magnetic flux and the amount of loops in the circuit/coil.
ε ~ dφ/dt
ε ~ N
Meanwhile, Henry stated that EMF is generated whenever a closed circuit experiences a change in electric current. The EMF generated is directly proportional to the change in current and the inductance of the inductor.
ε ~ di/dt
ε ~ L
Several years after their discoveries, Emil Lenz stated a new law that predicts the direction of the EMF-induced current. He states that the electric current induced by EMF is such that it creates a magnetic field that opposes a change in magnetic flux.
EM induction is used a lot in our lives, such as the electric outlets in your house! They're generated using a spinning electrical circuit in a magnetic field, which produces an alternating current of electricity that you use every day.
So, the next time you watch TV, charge your laptop, or just turn on some lights... maybe you'll remember this post—how the great scientists of the 19th century discovered a new way to generate electricity when they decided to play around with magnets and wires.