ELECTROMAGNETIC INDUCTION

• Magnetic effect: An electric current passing through a conductor produces a magnetic field around it.

• Electro motive force: When a cell is not connected to a load, the potential difference between the poles of the cell is called emf.

• SI unit of emf: volts• Device for measurement:

voltmeter

A quick revision..!!

Can a magnetic field produce an electric field..?

If yes then how..??If no then how..?? Any guesses..?Lets find out..!!

Michael Faraday, a British scientist has answered all your queries..!!

See how he has done it by just clicking here..

http://www.youtube.com/watch?v=KGTZPTnZBFE

What does electromagnetic induction mean..??

• When the magnetic field linked with a circuit changes, an electromotive force (e.m.f) will be induced in the circuit. This phenomenon is called electromagnetic induction.

• In a closed circuit an electric current will be produced. It is called induced current.

Factors influencing the induced emf..

The induced e.m.f in a coil increases with the increase in :• the number of turns of the coil• the rate of change of magnetic

field linking with the coil.

Faradays laws of electromagnetic

induction.. First law :- A changing

magnetic field linking a conductor induces an electro motive force in the conductor.

Second law :- The induced electromotive force is proportional to the rate of change of magnetic field linking the conductor.

Fleming’s right hand rule..

Fleming’s right hand rule gives the relationship between the directions of magnetic field, induced current and the direction of motion of the coil.

Thumb: Direction of Motion of the conductor

Index finger: Direction of magnetic Field

Central finger: Direction of the Current induced

An AC DYNAMO..!!

DEFINITION: A device that converts mechanical energy into electrical energy using the principle of electromagnetic induction is called a dynamo.

USES: It is used to get electric current.

The dynamo is usually fixed to the back wheel of a bicycle.

Lets see how it works in the next slide..

https://www.youtube.com/watch?feature=player_detailpage&v=HLNugJwBRow

WORKING OF AC DYNAMO

Check out this link to know it better..!!

When the working of AC dynamo is known its time to check out the working of DC dynamo..!!

Check out the link to know it better..https://www.youtube.com/watch?v=FRZQji5pxUs&feature=player_detailpage

If the Forefinger indicates the direction of magnetic Field and the Central finger

indicates the direction of electric Current, then the main finger indicates the

direction of Mechanical force acting on the conductor.

Fleming's left hand rule

https://www.youtube.com/watch?feature=player_detailpage&v=HLNugJwBRow

Lastly check out the working of the DC

motor..!!

Hope you enjoyed learning the topic..!!