Magnetic Effects of Electric Current

A generator converts mechanical energy into electrical energy, while a motor does the opposite, it converts electrical energy into mechanical energy. Both devices work on electromagnetic induction, i.e. emf is induced in the coil by a changing magnetic field.

A rectangular coil of insulated copper wire wound on a soft iron core is known as armature.

A commutator is a copper ring split into two parts which are insulated from each other and mounted on the tale of the motor and rotated with it.

The TGV, one of the world's fastest trains, is powered by electric motors.

According to Lenz’s law, the direction of induced emf is such that it opposes the change responsible for its production.

Whenever there is a change in the lines of force linked with the conductor, emf is induced in the conductor as long as the change lasts.

In an electric motor, two small strips of carbon known as brushes, press slightly against the two half rings and the half rings rotate between the brushes.

Electromagnetic induction was discovered by Faraday.

The magnitude of the induced emf or current depends on the rate of change of magnetic flux through the coil.

If the circuit of the conductor is closed, then a current flows in the conductor due to the induced emf between the two ends. The current produced is called induced current.

The other name for generator is dynamo.

The electrochemical cell which cannot be recharged is called primary cell.

Field magnet is a strong horseshoe permanent magnet.

The number of rotations produced in one second is called the frequency of the alternating current.

The alternating emf (or current) is that which changes in magnitude and direction periodically.

The alternating emf is minimum, whenever the plane of the coil is instantaneously perpendicular to the magnetic field.

If the armature rotates 30 times in one second, the frequency of the alternating emf produced is 30 Hz.

High powered electrical appliances are earthed to avoid shock.

The process by which alternating current is converted into direct current is called full wave rectification.

Direction of induced current produced by motion of a conductor in a magnetic field is given by Fleming's right hand rule.

AC power can be increased or decreased in voltage by using a transformer.

Electromagnets used in hoisting cranes are very powerful and those used to remove iron filings which accidentally get into the eye are very weak.

A term formerly used for direct current was galvanic current.

Magnitude of induced emf is directly proportional to the strength of the inducing magnet, number of turns of coil and area of cross-section of coil.