Electromagnetic Induction

Electricity and magnetism were considered separate and unrelated phenomena for a long time. In the early decades of the nineteenth century, experiments on electric current by Oersted, Ampere and a few others demonstrated that a current carrying conductor is associated with a magnetic field. Thereafter, attempts were made to verify the reverse effect of producing an induced emf by the effect of magnetic field.

Michael Faraday demonstrated the reverse effect of Oersted experiment. He explained the possibility of producing emf across the ends of a conductor when the magnetic flux linked with the conductor changes. This was termed as electromagnetic induction. The discovery of this phenomenon brought about a revolution in the field of power generation.

Magnetic Flux:

· The magnetic flux (φ) linked with a surface held in a magnetic field (B) is defined as the number of magnetic lines of force crossing a closed area (A) as shown in figure.

· If θ is the angle between the direction of the field and normal to the area, then,

· The SI unit of magnetic flux is weber (Wb) or tesla meter squared (T ).

· Magnetic flux is a scalar quantity.