1. Solar Bottle Lights

2. What do you think houses are like in rural Uganda? Many houses are built using mud and have thick thatch roofs. They also have very few windows, so are often very dark.

4. Watch the Video What happens when the bottles are put through the ceiling? https://vimeo.com/34607729

5. Time to Make your own Solar Bottle Light

6. Take the Solar Bottle Light out of the box and cover the hole in the top, how much light is there in the box? Uncover the hole in the top, how much light is there now? Put the Solar Bottle Light back through the hole, how much light is there now? Testing Your Solar Bottle Light

7. What is happening? The process is called light refraction. Light refraction occurs when light passes from one material to another i.e. when light travels from air to water.

8. When a light wave moves from one material to another (i.e. air to water) it slows down. This causes the light to change direction i.e. rather than travelling straight down through the water, it travels diagonally.

9. This means that when we look at things below the water they are distorted (they appear differently to how they really look). Look at how the straw below appears to be in two pieces.

10. So, why does the Solar Bottle Light increase the amount of light that comes into the room? Draw a diagram of the Solar Bottle Light to show what happens to the light waves when they go through the water. Draw 3 light waves going down through the bottles and into the box.

11. Light source

12. If you only had a hole in the roof then the light waves would go straight down However, because the light waves are travelling through air and then water, they are travelling diagonally into the room. This means the light waves spread out and allow more light to enter the room.

13. The original Solar Bottle Light was invented by Alfredo Moser in Brazil To learn more about his invention, watch the video: http://youtu.be/owsZxIVc9DE

14. Find more resources at: sendacow.org.uk/lessonsfromafrica Follow us @SACeducation