Edexcel GCSE Physics 1PH0
Key Concepts of Physics
Motion and Forces
Conservation of Energy
Waves
Light and the Electromagnetic Spectrum
Radioactivity
Astronomy
Energy – Forces Doing Work
Forces and Their Effects
Electricity and Circuits
Static Electricity
Magnetism and the Motor Effect
Electromagnetic Induction
Particle Model
Forces and Matter
Electromagnetic Induction
How a transformer works
- 3 things to know
- Paper 2
Overview
The construction of a transformer, how an alternating current in the primary coil induces a potential difference in the secondary, why direct current gives no output, the soft iron core, and step-up and step-down transformers and their turns.
What you need to know
Answer each one before you reveal it.
Explain why a transformer produces no output when a steady direct current flows in its primary coil.
Explain why the two coils of a transformer can be electrically insulated from each other and still transfer energy.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Describe the basic construction of a transformer.
Model answer
Two coils of insulated wire, called the primary and the secondary, are wound on a core of soft iron.
- 2
Explain how an alternating current in the primary coil of a transformer induces a potential difference in the secondary coil.
Model answer
The alternating current creates a continually changing magnetic field in the core, and that changing field induces a potential difference in the secondary coil.
- 3
Explain why a transformer produces no output when a steady direct current flows in its primary coil.
Model answer
A steady current gives an unchanging magnetic field, and only a changing field can induce a potential difference.
- 4
State the purpose of the iron core in a transformer.
Model answer
It carries the changing magnetic field from the primary coil across to the secondary coil.
- 5
Explain why the two coils of a transformer can be electrically insulated from each other and still transfer energy.
Model answer
The energy is carried between them by the changing magnetic field, not by charge flowing from one coil to the other.
- 6
Name the coil of a transformer that is connected to the input supply.
Model answer
The primary coil.
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