aquarian-nrp
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### Colors and Absorption of Heat

My experiment was testing the the heat absorption of colors. I used glass quart canning jars with water, lid, and a heat lamp. I wrapped quart jars with various colors of construction paper and then set each jar 18" from a heat lamp for 30 minutes and measured the temperatures at the end of 30 minutes. (Each jar was done one at a time).

For a second test, I used glass quart canning jars, with lids, but colored the water with food coloring and did not wrap the jar with construction paper.

The heat temperatures for the jars containing water and food coloring were anywhere from 7-9 degrees higher than the jars that I wrapped with construction paper. (Same test was used, 18" from heat lamp, lids, and heat for 30 minutes).

I would like to know if my hypothesis is correct that the construction paper acted as an insulator and/or filter of the heat light and that is why the jars covered with construction paper had lower temperatures than the jars without construction paper, but colored water.

I also have a question regarding the construction paper wrapped jars. Black, purple and blue had the highest temperatures. I was surprised to see that orange was very close to the temperatures of black, purple and blue. I don't understand why orange also had a high temperature. Would you have an explanation as to why the jar with the orange construction paper wrapping would measure similar temperatures as the black, purple, and blue construction paper wrapped jars?

Thank you.

kgudger
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### Re: Colors and Absorption of Heat

Hello and welcome to the forums.

This sounds like an interesting project.

With regards to the various colors which absorbed the most heat, I think the main consideration might be how dark those colors were. I would think that blue and purple would not absorb so much; unless they were very dark blues and purples. Here is a spectrum analysis of heat lamps: http://heelspurs.com/a/led/black3.gif which shows, as you might expect, that heat lamps emit the most energy in colors towards the red end of the spectrum, as expected. That would explain orange - did you also try red?

Why did the colored liquids absorb more heat than the paper covered ones? I hope other experts can chime in on this, but consider how the heat absorption works. With the paper, a part of it is exposed to the heat, and the paper absorbs the energy, transfers it to the glass (and may have some air between the two, also), which then transfers it to the water. In the colored water case, the heat absorption happens right in the water, which should be more efficient. Did you have a control with no coloring? How much did that one heat up?

Best, Keith

dpututor
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### Re: Colors and Absorption of Heat

Hello!
I see that your experiment deadline has passed, but I would really be interested in hearing what your results were regarding the colored liquid and the paper covered liquid! I agree with Keith's explanation for why the colored water would have absorbed more heat.