The sun is the source of all energy on Earth!
Let’s explore some solar power!
Water Still
Supplies:
- Large bowl
- Smaller bowl or cup
- Plastic wrap
- Small rock or other object that weighs enough to push down the plastic wrap, but not too heavy to put a hole in it.
- water
- Salt
- spoon
Experiment:
- Place the smaller bowl or cup into the center of the larger bowl.
- Add water to the large bowl till it reaches about ⅔ of the smaller cup or bowl. The smaller bowl/cup must stay empty.
- Pull the smaller bowl/cup out of the larger bowl to make it easier to do the next step.
- Add salt a tablespoon at a time until the water can no longer absorb the salt and it starts to settle at the bottom.
- Taste your water. How does it taste?
- Add the smaller bowl/cup back into the center of the bottom of the larger bowl.
- Leave the smaller bowl in the large bowl and cover the large bowl with plastic wrap.
- Take the rock or other weighted object and place it in the center of the plastic wrap so that it pushes down on the wrap towards the smaller bowl or cup.
- Carefully place your Water Still in the sun. Leave it there for a few hours and observe.
- After a few hours, notice what is collected in the smaller bowl/cup. Taste what’s in the smaller bowl/cup. What do you notice?
But Why!?
The water at the bottom of the larger bowl is full of salt, but the water that ended up in the smaller bowl/cup was not. Did you notice when the sun was shining on the bowl that there were water droplets all around the bowl?
That water was evaporating from the water at the bottom of the bowl and condensing again on the plastic wrap. Because of the weight in the middle of the wrap, the water that condensed on the plastic wrap slid down towards the lowest point and dripped into the smaller bowl/cup where it collected.
The water in the smaller bowl/cup no longer had the salt because the salt doesn’t evaporate the way the water molecules do! The only thing that ends up in the bowl/cup is the water without the salt!
Fading Colors
Supplies:
- Construction paper
- Every color of the rainbow
- Try white and black as well!
- Random solid objects that won’t melt in the sun
- To control the variables, try using all of the same objects for each piece of construction paper.
- For example: blocks, rubber duckies, coins
- To control the variables, try using all of the same objects for each piece of construction paper.
Experiment:
- Lay a sheet of each color paper out in the sun.
- Place a solid object on each piece
- Leave the paper in the sunlight for several hours
- Remove the objects from each piece of paper and observe.
- What color paper faded the most? Or the least?
But Why!?
The colors that we see are the wavelengths being reflected back to us. That means that the other wavelengths are being absorbed. Each color has a different amount of energy. Red has the least amount of energy, so it absorbs the most. Purple reflects the most energy, so it absorbs the least.
When the sun hits these colors, the red is absorbing the most energy, so it breaks its chemical bonds of its colors faster than the purples that are reflecting and not absorbing the energy, so it can hold its bonds longer.
Since the blue and purples are reflecting the most energetic wavelengths instead of absorbing them, the chemical bonds aren’t as affected as the red and orange colors. The reds and oranges are the colors that fade quickest.
So, what about black and white? What’s your hypothesis?
Black absorbs all of the colors and white reflects them, which do you think will fade faster?