Lesson 4 of 7
Lenses and the eye
Goal: Describe how a convex lens and the eye focus light.
A convex lens bends rays of light towards each other. Your eye uses one to focus light on to the retina.
- A convex lens is thicker in the middle than at its edges. It refracts parallel rays so that they meet at a point, called the focus.
- In your eye, the cornea and the lens focus light on to the retina. The image there is upside down, as it is in a pinhole camera. Your brain makes sense of it the right way up.
- The retina detects light. Its cells absorb the light that lands on them. This causes chemical changes, which send electrical signals along the optic nerve to the brain.
- A camera works like an eye. Its lens focuses light on to a sensor, which turns the light into electrical signals.
Your turn
Check yourself
Knowledge organiser
This lesson on one page. Tap it to make it bigger.
Key words in this lesson
Ray A straight line with an arrow that shows the path of light
Convex lens A lens, thicker in the middle, that bends rays towards each other
Retina The layer at the back of the eye that detects light