I have wanted to experiment with solar power for a while now, but Finland is not the best place for these experiments. Most of the year the sun shines here at such an angle through the atmosphere that there isn’t enough of sun power for good experimentation. However, we do get some really warm and sunny days in the summer. So here are two solar experiments that have worked even in Finland during a really warm and sunny day.
Pizza box solar oven
I got the idea for this experiment from homesciencetools.com HERE. It is a shop online selling equipment for this kind of experimentation. They have good content on their site and good ideas for experimentation as well. This experiment teaches about absorption of light waves, about reflecting sunlight, about insulation, different wavelengths of visible light and also infrared, which is felt as heat.
So to build a pizza box solar oven you need a pizza box. You also need some black cardboard, tinfoil, tape, scissors or another way to cut cardboard, some newspaper, some plastic wrap, and a way to measure temperature.
Building the oven:
- Cut a flap on the top of the pizza box.
- Cover the inside of the flap with tinfoil. The tinfoil helps in reflecting sunlight into the pizza box oven.
- Cover the opening made into the top of the pizza box with the plastic wrap and attach with tape. This helps preventing heat to escape the oven. Don’t leave any openings for hot air to escape.
- Place the black cardboard on the bottom of the oven. This black cardboard helps to heat the oven as black absorbs lightwaves best.
- Finally put some newspaper on the sides of the pizza box to act as insulation – also helping to keep the warm air in the oven.
- Place outside in a sunny place. You may need to adjust the flap and tilt the oven for best outcome.
We tried this to heat a piece of toast (below). The temperature inside the oven was 25 Celsius degrees when we started and it rose to 57 degrees Celsius within 30 minutes. Then it stopped rising. I asked daughter to wait until the cheese had melted a bit, before submitting to her requests to eat the bread.
This kind of oven is ok in Finland to warm something up a bit, but in places such as India or basically anything near the equator, it can be used to cook stuff.
Next we built a solar purifier. As this came after the states of matter, this also worked as a reminder for concepts such as vaporisation and condensation. To build a solar purifier you need a container for the liquid. We used a dark blue vat, because the dark colour absorbs more lightwaves than a lighter one. Then you need water, plastic wrap, a smaller container, and some pebbles.
- Put water into the container
- Have the kid put all kinds of stuff into the water. We put in soil, flowers, and grass. This was daughter’s favourite part.
- Place the smaller container in the middle of the now filthy water.
- Cover the entire container with plastic wrap. This contains the water vapour that then condenses on the plastic wrap. It condenses there because the air outside the container is cooler than the air inside it.
- Put some pebbles on top of the plastic wrap. As liquid flows downwards, the pebbles help the water to drop into the smaller container.
- Just wait and the water will vaporise from the filthy water making water vapour. This then will condense mostly on the plastic wrap and flow downwards into the smaller container.
We let it sit there in the sunlight for the rest of the day and came to see the results in the evening. The water inside the smaller container is clean water we could drink. There wasn’t a lot of it, but enough to prove the concept.
If you try these experiments at home and your child asks questions, please let me know what types of questions they ask in the comment section so I can further develop these instructions. If you have questions about these experiments or instructions, leave me a comment and I will answer and also improve these instructions. Also, please remember like and share if you find this useful.
Copyright text and images: Satu Korhonen. You are free to try these experiments out, use them in your teaching. But instead of copying the text or images, link back to this page.