Electromagnetic Induction

Chapter 1

Electromagnetic Induction

 Electromagnetic induction: - It is the phenomenon in which an emf is induced in a conductor because of change in linked magnetic field.

 Dynamo: - It is a device which converts mechanical energy into electrical energy using electromagnetic induction.

 Dynamo Rule: - Fingers of right hand are stretched such that the forefinger, middle finger, and the thumb point perpendicular to each other. If the forefinger points in the direction of magnetic field (from North Pole to South Pole) and the thumb points in the direction of motion of the conductor, then the middle finger

shows the direction of induced current.

 Motor Rule: - Fingers of left hand are stretched such that the forefinger, middle finger, and the thumb point perpendicular to each other. If the forefinger points in the direction of magnetic field and the middle finger points in the direction of current, then the thumb shows the direction of force.

 Commutator: - It consists of split rings which change contact from one brush to another after every half rotation to help current flow in the same direction in an external circuit.

 A.C. Current: - Current whose direction reverses after every half cycle is called A.C. current.

 Faraday’s First Law of electromagnetic induction: - A changing magnetic field linked to a conductor induces emf inside it.

Faraday’s Second Law of electromagnetic induction: - The induced emf is proportional to the rate of change of magnetic field linked to a conductor.

 Electric motor works on the principle that a current carrying conductor when placed inside magnetic field experiences mechanical force.

 Dynamo works on the principle of electromagnetic induction.