Transformers [H]

Transformers are devices that change the potential difference (voltage) of an alternating current supply. They are essential for the efficient transmission of electricity through the National Grid. This is Higher tier content from AQA GCSE Physics specification 4.7.3.

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What Is a Transformer?

A transformer is a device that changes the potential difference (voltage) of an AC supply. It consists of:

• A primary coil — the input coil connected to the AC supply.
• A secondary coil — the output coil connected to the device or load.
• An iron core — links the two coils magnetically.

The primary and secondary coils are not electrically connected — they are linked only through the magnetic field in the iron core.

graph LR
    subgraph "Transformer"
        AC["AC Supply"] --> PC["Primary Coil (n_p turns)"]
        PC -->|"Changing magnetic field in iron core"| CORE["Soft Iron Core"]
        CORE -->|"Induces p.d. in secondary"| SC["Secondary Coil (n_s turns)"]
        SC --> LOAD["Load / Output"]
    end

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How a Transformer Works

Step-by-Step Explanation