Why can't we see in the dark?

Have you ever wondered why we can’t see in the dark?

We need light to see the world around us but how do our eyes use light to see?

Watch the video with Catriona demonstrating how to make a pinhole camera or pinhole theatre to find out.

Here is what you need to make a pinhole camera

• pins
• scissors or a craft knife (adult supervision required)
• aluminium foil or tin foil
• tracing paper or baking paper
• black tape
• shoe box or any long small box

Instructions on how to make a pinhole camera

• Make the shoe or small box light proof by using black tape to cover the gaps around the outside of the box. Make sure all the gaps are covered with black tape.
• Cut out a square on one side of the box (about 8cm x 8cm) and stick baking paper or tracing paper in its place using black tape. This is the screen where the image will appear.
• Use a pin to make a hole on the side of the box opposite the side with the baking paper/tracing paper.
• Point the pinhole at a bright object like a candle or something bright outdoors on a sunny day. What do you see?

You should see an inverted or upside-down image of your surroundings on the baking paper/tracing paper or the screen just like Catriona did!

Challenge

Can you make a larger version of the pinhole camera and make a pinhole theatre so you can put your whole head inside the box just like Catriona? What would you expect to be different?

Make a pinhole theatre using aluminium foil as shown in the video so you can make changes to the pinhole. Watch the video again to see how to make a pinhole theatre using aluminium foil.

1. Guess what might happen to the image if the hole in the pinhole theatre is made larger? Make the pinhole larger and see what happens.
2. Guess what might happen to the image if the hole is a different shape? Make the pinhole a different shape and see what happens.
3. Guess what might happen if you put multiple holes in your pin hole theatre? Make multiple holes and see what happens.
4. Write down three new facts you learned about light and how it behaves after doing this activity.