Transformers: Structure & Operation

What is a transformer?

A device that uses electromagnetic induction to change an alternating potential difference.

What are the three main parts of a basic transformer?

A primary coil, secondary coil and iron core.

What is the primary coil?

The coil connected to the input alternating potential difference.

What is the secondary coil?

The coil across which the output potential difference is induced.

What is the purpose of the iron core?

To carry the changing magnetic field between the two coils.

Why is iron used in a transformer core?

It is easily magnetised, allowing it to carry the changing magnetic field effectively.

How does a transformer work?

An alternating current in the primary coil produces a changing magnetic field, inducing a potential difference across the secondary coil.

Why must the magnetic field change for a transformer to work?

A changing magnetic field is needed to induce a potential difference.

Why does a transformer normally require alternating current?

Alternating current produces a continually changing magnetic field.

Will a transformer work continuously with a steady direct current?

No, steady DC does not produce a continually changing magnetic field.

What happens when alternating current flows through the primary coil?

It creates a changing magnetic field in the iron core.

What happens in the secondary coil?

The changing magnetic field induces an alternating potential difference.

Are the primary and secondary coils directly electrically connected in a basic transformer?

No, energy is transferred through the changing magnetic field.

What determines whether a transformer increases or decreases potential difference?

The ratio of turns on the secondary and primary coils.

Why does the number of turns affect the output potential difference?

The induced potential difference depends on the number of coil turns linked by the changing magnetic field.

What is the main energy transfer in a transformer?

Electrical energy is transferred from the primary circuit to the secondary circuit.

Why are transformers useful?

They allow alternating potential differences to be increased or decreased efficiently.

What happens to energy in a real transformer?

Some energy is dissipated to the surroundings, so output power is less than input power.