1) How Rainbows Are Formed
What you need
- Washable crayons*
- Torch* (you can use the torchlight function in mobile phones)
- Dark room*
- Drawing paper*
Step by Step
1. Fill the bowl with water and put it in a dark room near the wall.
2. Stick the drawing paper on the wall using blu-tack.
3. Open up the mirror such that it forms an 'L' shape and place it into the bowl of water.
4. Shine the torchlight directly at the side of the mirror that is fully submerged in the water.
5. Adjust the angle of the other side of the mirror until a rainbow is reflected on the drawing paper.
6. Quickly draw lines to capture the rainbow and colour directly on the drawing paper with the washable crayons.
A rainbow is created when white light is bent (refracted) while entering a droplet of water, split into separate colours, and reflected back.
Water and other materials bend the different colours at different angles, some more strongly than others.
When the light passes through the water, it bends and the 7 colours are reflected from the mirror to the wall!
What you need
- Food colouring** (red, yellow and blue)
**Items provided in the Colour Mixing Challenge
Step by step
1. Place the 7 cups in a row and fill the first, third, fifth and seventh cup with 80ml of water.
2. Add 5 drops of red food colouring to the first and seventh cup. Stir evenly.
3. Add 5 drops of yellow food colouring to the third cup and stir evenly.
4. Add 5 drops of blue food colouring to the fifth cup and stir evenly.
5. Take a filter paper and fold it into half and in half again lengthwise. Repeat until you have folded all 6 filter papers.
6. Place one end of the folded filter paper in the first cup and the other end in the second cup (make sure the ends of the filter paper touch the bottom of the cups).
7. Continue Step 6 until you have placed the last filter paper in the sixth and seventh cup.
8. Observe and watch the rainbow relay happen right before your very eyes!
The filter paper is made from fibres and the water is able to move through the gaps in the fibres. The gaps in the filter paper help to pull the water upwards.
Each raindrop makes its own rainbow but it takes millions of raindrops for us to see a rainbow.
There is no end to a rainbow. Rainbows are actually full circles. We only see an arc (part of the circle) because we usually view rainbows from the ground.
Occasionally, passengers in a low-flying aircraft see rainbows that form complete circles!