Enrichment Activity for 5-11 11-14
What you need
- 10cm x 10cm piece of card
- Aluminium foil
- Sticky tape
- Pin or needle
- Computer or phone screen
- Cut a shape about 3cm square from the card, tape foil across the gap and make a tiny pinhole in the foil.
Results and Explanation
When you hold the card close to you and look through the pinhole at some writing on the screen, it should be magnified and sharper, though it will be dimmer.
The closer you are to an object, the larger the image it makes on the back of your eye, but get too close and the image will be fuzzy, because your eye does not bend all the light rays coming in by enough to focus them into a sharp image.
A pinhole cuts down the spread of light rays entering your eye so your lens focuses the rays coming through a smaller area and a sharp image forms on the back of your eye.