May 24, 2016

What can the Sun Melt? An Experiment in Concentrating the Sun's Energy

Somewhere my children learned you could set fire to things using a magnifying glass and the sun's energy. Where exactly do they learn these things? I would assume a book, but they learned it nonetheless, and they wanted to try it! Of course, I did NOT want to try setting something on fire, so we decided to try to melt things instead.

I gave each of the girls a plate with a large marshmallow, a small 3 Musketeers candy bar, and a section of a Hershey's milk chocolate bar. We started by just leaving these in the sun for about 30 minutes. I was willing to leave them longer, but the girls wanted to get on with the experiment. So out they went with magnifying glasses.

It took them a little while to get the angle it took to concentrate all the sun's rays on to the little treats. Once they did they impatiently held the magnifying glass there for a couple minutes. It really was just a couple minutes. Maybe we would have seen more results if the kids were a bit more patient, but we did see results!

First up the marshmallow. The girls thought it would grow like it does in the microwave, but after a couple minutes with the magnifying glass it remained. Slightly warmer, but still marshmallow shaped. 

Next, the 3 Musketeers, this they thought would melt because it is chocolate wrapped in chocolate after all. After a couple minutes it was slightly softer to the touch, but it held it's shape.

Lastly, the milk chocolate. Like the previous chocolate, they figured this one would melt, and this time they were right. After just a couple minutes the milk chocolate was showing definite signs of melting. 

It was even more obvious when they stuck their fingers in it, and their fingers ended up covered in chocolate! Not that they minded licking them in the least!

The secret to making this work, just like the secret to lighting things on fire, is to hold the magnifying glass at an angle to the sun. When you have the right angle, a small bright dot will appear on whatever you are trying to heat up; the sun's energy is all concentrated on that dot. The smaller the dot, the stronger the energy! Now that you know, what will you melt?

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