Electromagnetic Induction class 10 notes | cbse24

The production of electricity from magnetism is called electromagnetic induction.

Example:-When a straight wire is moved up and down rapidly between the two poles of a horseshoe magnet, then an electric current is produced in the wire. This is an example of electromagnetic induction. Again, if a bar magnet is moved in and out of a coil of wire, even then an electric current is produced in the coil. This is an example of electromagnetic induction.

The process of electromagnetic induction has led to the construction of generators for producing electricity at power station. 

Note:-

• A galvanometer is an instrument which can detect the presence of electric current in a circuit.
• Galvanometer can detect both electric current and voltage, both.
• If we connect galvanometer in series, it detects current.
• If we connect galvanometer in parallel, it detects voltage.

[1] To Demonstrate electromagnetic induction by using a straight wire and a horseshoe-type magnet

The above experiment shows that when the direction of motion of the wire in the magnetic field is reversed, then the direction of induced current is also reversed. Please note that the direction of induced current in the wire can also be reversed by reversing the position of poles of the magnet, which means that the direction of induced current can also be reversing the direction of magnetic field.

• The movement of a wire in a magnetic field can produce electric current.
• A generator uses the movement(or rotation) of a rectangular coil of wire between the poles of a horseshoe magnet to produce an electric current(or electricity)

[2] To Demonstrate electromagnetic induction by using a coil and bar magnet.

The production of electric current by moving a magnet inside a fixed coil of wire is also a case of electromagnetic induction. The concept of a fixed coil and rotating magnet is used to produce electricity on large scale in big generator of power houses.

The condition necessary for the production of electric current by electromagnetic induction is that there must be a relative motion between the coil of wire and a magnet.

After performing a large number of experiments, Faraday and Henry made the following observations about electromagnetic induction.

• A current in induced in a coil when it is moved(or rotate) relative to a fixed magnet.
• A current is also induced in a fixed coil when a magnet is moved(or rotate) relative to a fixed coil.
• No current is induced in a coil when the coil when the coil and magnet both are stationary relative to one another.
• When the direction of motion of the coil ise reversed, the direction of current induced in the coil also gets reversed.
• The magnitude of current induced in the coil can be increased

           (a) By winding the coil on a soft iron core.

           (b) By increasing the number of turns in the coil.

           (c) By increasing the strength of magnet.

           (d) By increasing the speed of rotation of coil.