Key learning points

1. The human eye is a sense organ that detects light to enables us to see.
2. The functions of the cornea, iris, lens, ciliary muscles, retina and optic nerve.
3. Interpretation of ray diagrams showing refraction, to explain how the eye focuses light onto the retina.
4. The iris expands and contracts (a reflex response) to control the amount of light entering the eye through the pupil.
5. Use appropriate techniques to investigate the size of the pupil in different light levels.

Keywords

• Lens - An object that can focus light rays. In the eye, it brings light rays to focus on the retina.

• Refraction - Occurs when light travels from one transparent medium to another, causing a change in direction.

• Focus - The process of bringing light rays together to converge at a single point creating a clear image.

• Focal point - The point where rays of light meet after passing through a lens.

• Reflex response - An involuntary, fast neural response to a situation.

Common misconception