## Absorption of Radiant Energy by Different Colors. HELP!

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### Absorption of Radiant Energy by Different Colors. HELP!

Hello, so as you can see, this is my experiment. It is due in 5 days, and I haven't started. I know, I'm a procrastinator.
So I got the temperatures of the color and all, but on step 7, it says "calculate the energy flow and the energy carried by the visible and infrared photons."
How do I do this? Is there supposed to be a special feature on the infrared thermometer or something? I would gladly appreciate it if someone could help.
Also, I do not know how to do any steps after that. How do I find out the photons it emits by the temperature in degrees Fahrenheit or Celcius.
Can you please get back to me soon? I only have five days to complete this. Thank you.
MrBubbles

Posts: 3
Joined: Tue Feb 19, 2013 10:24 am
Occupation: Student
Project Question: Absorption of Radiant Energy by Different Colors
Project Due Date: 02/24/13
Project Status: I am just starting

### Re: Absorption of Radiant Energy by Different Colors. HELP!

Hi MrBubbles,
If you check on the "background" page of your experiment:
http://www.sciencebuddies.org/science-f ... background
there is a very nice example of how to calculate the energy flow and energy carried by the photons. See the section under "Equation 2."

There should be a way to switch your thermometer back and fourth between Fahrenheit and Celsius.

Power is energy flow, or the rate of energy emission. When calculating the power with equation 2, you will need to make sure that you express your temperatures in Kelvin. There is also an explanation on the background page how to convert Celsius to Kelvin. In equation 2 "T" is the temperature of the colored square that you measured, and "Ts" is the temperature of the surroundings - basically just the room temperature - you also need to convert this to Kelvin.

Let us know if you get stuck
Good Luck!

matthew
matthewgettemy
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Occupation: Student-Grad School Physics Education, Lab Technician-PPG
Project Question: I am registering to be a Science Buddies Adviser
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Project Status: Not applicable

### Re: Absorption of Radiant Energy by Different Colors. HELP!

Thank you so much, you are a lifesaver! I do not have time to finish this experiment, but I will get back to you as soon as I can with my results. I know I will have problems, but I really appreciate your help. Do you think it is possible for you to answer any other further questions I may have? Thank you, once again. You have really helped me, and i may be able to get my project done on time.
MrBubbles

Posts: 3
Joined: Tue Feb 19, 2013 10:24 am
Occupation: Student
Project Question: Absorption of Radiant Energy by Different Colors
Project Due Date: 02/24/13
Project Status: I am just starting

### Re: Absorption of Radiant Energy by Different Colors. HELP!

Yeah sure!
I do not log on every day, but someone will probably be able to help you.
I will try to log on on every few days to make sure you are moving along smoothly.
Try to follow the example provided very closely with your own data.

matthew
matthewgettemy
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Posts: 8
Joined: Sat Dec 01, 2012 11:38 am
Occupation: Student-Grad School Physics Education, Lab Technician-PPG
Project Question: I am registering to be a Science Buddies Adviser
Project Due Date: n/a
Project Status: Not applicable

### Re: Absorption of Radiant Energy by Different Colors. HELP!

I was working on my experiment and I got stuck. During my presentation, I will have to answer a few questions.
One of them is how will this this help us in a real world situation?
Another one is what is the control experiment? I think it is the white paper.
Also, what are the independent and independent variables?
I will have to explain to my class about radiant energy and what it is, and everything. Do you have any sources I can use?
Also, I don't understand number 10 of the procedure.
On the HyperPhysics website, it asks me for the emissivity. I do not know how to find that.
I will obviously have more questions, but this is all I have so far. I do not know yet. I am sorry there are so many questions, but this is really important as my grade on the project is really weighed heavily on my report card, and I don't want to ruin my 99 average.
MrBubbles

Posts: 3
Joined: Tue Feb 19, 2013 10:24 am
Occupation: Student
Project Question: Absorption of Radiant Energy by Different Colors
Project Due Date: 02/24/13
Project Status: I am just starting

### Re: Absorption of Radiant Energy by Different Colors. HELP!

Hi, MrBubbles,

First thing first, don't panic! I'll try to address your questions one by one.

1) How will this help in a real world situation?
Take another good look at the Introduction of the project page. It's got great info on the Sun and radiation, and how both are necessary for life as we know it. Also, this is basically a "real world" project; radiation is the focus of study for several fields, including, but not limited to, energy and photonics engineering.

2) What's the control? Independent/dependent variables?
I don't want to give too much away, since the only way you'll learn is by figuring them out using what you already know. And I'm pretty sure you know what the control and IV/DV are, but here's a quick refresher: the control is something kept constant throughout the experiment. The IV is what you change (hmm... maybe color?), in order to observe and make conclusions about the DV.

3) I will have to explain to my class what radiant energy is. Do you have any sources I can use?
If you scroll down to "Bibliography" on http://www.sciencebuddies.org/science-f ... background, you'll see a list of sources available for reference. Of course, by no means are you limited to just those. Do a Google search if you want to find out more, but don't have much time left!

4) I don't understand #10 of the procedure. On the HyperPhysics website, it asks me for the emissivity. I do not know how to find that.
#10 says, "Graph the power output of each square. Since power depends on the fourth power of the temperature, a small difference in temperature can cause a big difference in power output." I don't believe that, for the purpose of this project, you need emissivity. All you need is P = σ A(T^4 - (Ts)^4); refer to the project page again, under the part that reads "Equation 2." You should already have the temperatures, the area of the squares, and the Stefan-Boltzmann constant. Now just plug in the values and find the power outputs!

I think I've covered everything, but if you have more questions, feel free to ask! Hope this helped and good luck!
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Enjoy!
-RM, Expert
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