Whenever the magnetic lines of force passing through a closed circuit change, a voltage and hence a current is induced in it. This phenomenon is called electromagnetic induction. It was discovered by Michael Faraday in 1831

It is a device to convert electrical energy into mechanical energy. It is based on the principle that when a current carrying coil is placed in a magnetic field, it experiences a force.

The law states that while stretching the three fingers of left hand in perpendicular manner with each other, if the direction of the current is denoted by middle finger of the left hand and the second finger is for direction of the magnetic field then the thumb of the left hand denotes the direction of the force or movement of the conductor.

If the current carrying conductor is held in the right hand such that the thumb points in the direction of the current, then the direction of the curl of the fingers will give the direction of the magnetic field.

The region around a magnet within which its influence can be experienced is called magnetic field.

Pieces of iron and other magnetic materials which can be made to acquire the properties of natural magnets are called artificial magnets

It is a piece of lodestone, which is a black iron oxide (Fe₃ O₄) called magnetite. The word lodestone means a leading stone.

The substances which have the property of attracting small pieces of iron, nickel, cobalt etc, are called magnets and this property of attraction is called magnetism

The number of magnetic field lines crossing unit area kept normal to the direction of field lines is called magnetic flux density. Its unit is Wb/m².