## Wednesday, September 7, 2016

### Electromagnetic Induction Reasons and Explanations

Electromagnetic induction is a phenomenon of generation of electric current and EMF in a closed circuit when the magnetic flux linked with the closed circuit changes.

Michelson Faraday discovered that the change in magnetic flux in any closed circuit generates electromagnetic force or a potential difference in a closed circuit.

To explain this we can consider a small experiment consisting of two coils wound around a wooden core. The first coil consists of a battery and key. The second coil consists of galvanometer. It is experimentally observed that as long as constant current is passing in the first coil, the galvanometer shows the zero deflection. It means that there is no EMF generated in the secondary coil.

When the key the first closed coil is just closed, galvanometer shows some deflection and some EMF is generated. It is also noticed that even when the switch is just opened, galvanometer shows the deflection in the opposite direction. It means EMF is again generated and the current is generated in the opposite direction.

It can be noticed that when you just switch on or off the current in the first coil, there is a change in the current in that circuit. The current in the coil changes from zero to maximum value in small time. During this small time, the magnetic field around the closed coil changes. This changing magnetic field in the first coil produce a electric current and EMF in the neighboring circuit.

Magnetic flux

The number of magnetic lines of force passing through a given area of cross section normally is called magnetic flux and the magnetic flux per unit area is called magnetic induction. Magnetic flux is measured with a unit called weber and magnetic induction is measured with weber per meter square.

The magnetic field induction also depends on the angle between the magnetic flux and the area of cross section and it varies basing on it.

We can find its value for different angels as shown in the diagram below.

Its variation with different factors can be studied as shown in the diagram below.

The explanation can be further extended as shown in the diagram below.

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