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What is the Difference between Transformers and Rectifiers in Power Supplies?

In order to answer the question of 'what is the difference between transformers and rectifiers', we shall first need to recap on some fundamental background knowledge relating to electromagnetic induction.

Electromagnetic Induction

Electromagnetic induction describes the process of using a moving magnetic field around an electric conductor to create an electromotive force or EMF.

Discovery of electromagnetic induction is accredited to Michael Faraday in 1831 and, independently and almost simultaneously, by Joseph Henry in 1832.

Faraday demonstrated electromagnetic induction using a coil of copper wire wrapped around an iron core, the wire was attached to a galvanometer.

As he moved the magnet towards the coil, the galvanometer displayed a current, the direction of the current changes when the other pole was used.

Many electronic components use this principal, these include transformers, generators, motors and inductors.

In this article we are going to focus on transformers and rectifiers.


Transformers consist of two or more coils of wire, wrapped around an iron core that transfer electrical energy as a result of a changing magnetic field.

The iron core serves to magnify the effect of the field produced around the primary coil since iron is a temporary magnet so its poles are easily switched.

As the input voltage is alternating, the magnetic field induced will be changing direction with the same frequency ( 50Hz for mains electricity).

An emf will be produced in the secondary coil due to the change of magnetic flux.

Step up and Step down Transformers

There are two types of transformers, these are the step up and the step down.