The Human Eye

This lesson covers the structure and function of the human eye as required by the Edexcel GCSE Physics specification (1PH0), Topic 5: Light and the Electromagnetic Spectrum. You need to understand the main structures of the eye, how the eye focuses light, the process of accommodation, and how the eye compares to a camera.

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Structure of the Human Eye

The eye is a complex optical instrument. Each part has a specific function in forming a clear image on the retina.

flowchart LR
    subgraph EYE["The Human Eye — Structure"]
        A["Cornea<br/>Transparent front layer<br/>Does most of the refraction"] --> B["Aqueous humour<br/>Clear fluid behind cornea"]
        B --> C["Iris<br/>Coloured part<br/>Controls pupil size"]
        C --> D["Pupil<br/>Hole in centre of iris<br/>Lets light in"]
        D --> E["Lens<br/>Transparent, flexible<br/>Fine-focuses light"]
        E --> F["Vitreous humour<br/>Clear jelly<br/>Maintains eye shape"]
        F --> G["Retina<br/>Light-sensitive layer<br/>Contains rods and cones"]
        G --> H["Optic nerve<br/>Carries electrical signals<br/>to the brain"]
    end

    style A fill:#3498db,color:#fff
    style C fill:#9b59b6,color:#fff
    style E fill:#27ae60,color:#fff
    style G fill:#e74c3c,color:#fff
    style H fill:#2c3e50,color:#fff

Parts of the Eye and Their Functions