Solar power comes from the sun. Solar power can heat water, heat your home, provide electricity for lights, and many other things.
Solar power is a wonderful thing. It doesn’t cause pollution, we can’t run out of it unless the sun disappears, and it’s free.
How solar power works
Sunlight is filled with energy just waiting to be used. When the sunlight touches or shines on most things, the light starts giving off heat. EXAMPLE: when you sit on the beach playing in the sand, the sunshine heats up the sand and your skin.
When sunlight touches silicon or copper, the light turns into an electric current and makes electricity.
The power of sunlight
The sun’s light is very powerful. It can do a number of things. The sun’s light can:
- Change the color of something
- Dehydrate things (remove the liquid from something)
- Start a fire
Let’s see how the sun’s heat works to make all these things happen.
Putting sunlight to work
Here is what you need:
- Hot sunny day (at least 80 degrees F)
- 12 inch long piece of tin foil
- Cookie dough of your choice
- Dark colored sheet of paper
- Thinly sliced apple
- Piece of newspaper—preferably one with lots of printing/ink on it
- Magnifying glass
- Metal cookie sheet
Here is what you do:
Cooking with sunlight
- Place a 12 inch piece of foil on a concrete sidewalk, driveway, or paving stone; making sure it is in direct sunlight (the afternoon sun is best)
- Place 3 or 4 balls of cookie dough on the foil and press them to about 2 inches in diameter NOTE: you may place a piece of saran wrap over the dough to keep the bugs off if you wish
- Leave the cookies in the sun until they bake NOTE: the time needed to bake the cookies will depend upon how hot it is outside
- How long did it take the cookies to bake?
- Did they bake evenly?
Cooking with sunlight part 2
- Using the same foil you baked your cookies on, turn the edges up just a bit to form a ‘pan’ and lay the pan on a concrete sidewalk, driveway, or paving stone in direct afternoon sunlight NOTE: the hotter the day the better
- Break the egg open onto the foil
- You can watch the egg cook or leave and return in 10 to 15 minutes
- What part of the egg cooked first?
- How well did it cook in 10 minutes?
Using sunlight to change the color of something
- Cut a circle, heart, square or other simple shape from the edge of the colored sheet of paper
- Place the shape in the center of the paper; attaching it with clear tape to hold it in place
- Place the paper in a safe, dry location in direct sunlight NOTE: A window sill will do
- Leave the paper for 1 week
- After 1 week, carefully remove the shape from the center of the paper
- What happened?
Using sunlight to dry fruit
- Slice one half of an apple into thin slices—as thin as you or your parent can get them
- Place the apple slices on a metal baking sheet outside in direct afternoon sunlight
- Leave the apple slices in the sun for 24 hours NOTE: you can bring them in after the sun sets and return them the next day
- At the end 24 hours, what changes have taken place?
- If the apples are not dehydrated, leave them another 24 hours (taking them in at night)
Using sunlight to start a fire
- Place a piece of newspaper on a metal cookie sheet or on a concrete sidewalk, driveway, or paving stone in the direct afternoon sun (the hotter the day, the better)
- Hold a magnifying glass over the paper—concentrating on one spot and moving the magnifying glass farther or closer to the paper until a small circle of light is visible on the glass
- Continue to hold the magnifying glass over the paper in the same place
- The sun will burn a hole into the paper and begin to spread NOTE: the amount of time this takes depends upon the intensity of the sun’s heat
Here is what happened
- When baking the cookies and cooking the egg, the sun’s heat acted like an over or stove top. The foil reflected the heat back onto the cookie dough and the egg; giving them a ‘double dose’ of heat from the sun.
- Some of the sun’s light rays are ultraviolet rays. Ultraviolet rays are hot like the rest of the sun’s rays, but they also break down the chemical bonds of dyes that make things different colors. The ultraviolet rays break down the chemical bonds of the exposed paper, but not the paper covered by the cut-out.
- The sun dehydrates the fruit by pulling the juices out of it slowly.
- The magnifying glass concentrates the sun’s heat and light onto a small space.
When you combine heat and light like this, it mixes with the oxygen in the air. It actually collides with the oxygen in the air. This is called combustion. Fire is the result of combustion.
The sun is very useful, don’t you agree?