Basic Principle

Did you know that electrons act like tiny little magnets? Because each and every electron has a magnetic dipole moment. You don’t need to understand what is a magnetic dipole moment. The only important fact here is electrons act like tiny magnets, therefore like poles repel, opposites attract.

And then take a good conductor and a magnet. Next, move the magnet around the conductor, and it’ll cause electrons (the charge) to move. Congratulations, you have made electricity. But something seems wrong here. Instead of calling that it that we produce current or voltage, we usually call that EMF (electromotive force) is dynamically induced.

This is the basic principle that has used in practical electrical generators.

So, why is EMF (electromotive force)?

EMF is the force that drives electrons, and in other words, it’s is the measure of energy that it gives to each coulomb of charge. However, EMF is not actually a force or an energy. The word “force” is somewhat misleading, it is the potential to provide energy.

Or we can say that it’s the net voltage which can be generated using the power source.

The units of EMF is also volts.

So, why can’t we just call EMF as the potential difference?

Potential difference is the amount of energy used by the one coulomb of charge while the EMF is the measure of energy that it gives to each coulomb of charge.

However, EMF is equal to the terminal potential difference under one condition. If there is no current flow, EMF is equal to the terminal potential difference.

EMF is misleading

Electromotive Force – EMF can be misleading. Sometimes people read EMF as Electromagnetic Force and it’s completely a different concept. The electromagnetic force is the is a type of interaction that happens between electrically charged particles.

Other misleading factor is the word “force”. Electromotive Force – EMF is not an actual force or an energy.

EMF and the rate of change of magnetic flux

EMF is proportional to the rate of change of magnetic flux. So the change in magnetic flux causes EMF to be induced.

∅	Change in flux
N	Number of turns
t	Time taken
(∆∅)/Δt	Rate of change of magnetic flux

The EMF in a coil is equal to the negative of the rate of change of magnetic flux times the number of turns of the coil.

This relationship between the rate of change of magnetic flux and EMF is known as the Faraday’s law of induction.