Electromagnetic Induction
Principle of Electromagnetic Induction
Whenever the magnetic field in the region of a conductor is moving or changing in magnitude, electrons are induced to flow through the conductor, which creates an electric field.
The strength of the induced current is affected by the following factors:
- The number of turns in the coil
- The rate of change of the inducing magnetic field
- The strength of the inducing magnetic field
Induced Electromotive Force (EMF)
Consider a space where magnetic flux is changing with time, and we place a thin conducting loop inside it
An electric field will be created which will circle around the magnetic field.
The E-field will apply a force on the electrons in the conductor and they will start moving along the conducting path.
If there is a break in the loop, the charges will collect around the break, creating a voltage difference.
This induced voltage difference is called electromagnetic induction, also known as the induced electromotive force or induced EMF.
Induced EMF is the voltage difference of a wire created by magnetic flux changing over time
If we connect a resistor to fill the gap, the wire will act like a battery:
The induced EMF is given as:
which is nothing but Faraday's Law.
Types of Induced EMF
Flux can change for two reasons:
- The magnetic field itself changes with time. This is called a transformer EMF.
- The loop has motion. This is called motional EMF. The loop is either expanding, contracting, or rotating.
An alternative to the equation given above is using the Lorentz's force equation. However, force per unit charge if the definition of an electric field. Thus the induced E-field will be:
so the induced field is given as: