Science Buddies: "Ask an Expert"

I am currently working on a science fair project where I am building my solar panel and calculating the amount of energy coming in from different angles. I got the idea from the experiment "Getting something from nothing: free energy from the sun" but I am a bit confused on how to do the equations and the chart shown in the procedure. I would appreciate it if I can get help or any ideas. Thank you!

Hi Esmeralda and welcome to Scibuddies.

I looked at the diagrams and I'm not sure which 'thing' is supposed to represent the solar panel since it is not labeled. When I first looked at Fig. 3, i assumed that the red line was the solar panel. But then in Fig. 4, it says that a is the height of the solar panel above the table, and that is on the other part [??].

Rather than use Greek symbols for the angles, i'm going to call the one between the red plate and the table top, x, and the other one will be y. Now, the instructions say to first determine angle y and then subtract that from 180 degrees to get angle x. But why do it that way? It seems to me like all you have to do is measure the height of the solar panel [the red line in the diagram] from the table and the distance from where a vertical line from the end of the panel would hit the table top to where the end of the panel hits the table top. Then you can just use the formula:

x = aTan( b/a)

Just divide the height, b, by the length, a, and using a calculator or computer app, get the arctangent value in radians and convert that to degrees to find the angle. I like to use Excel for this. Let's say you measure the height, b, of the solar panel at its end and it is 22 cm. You mark where a vertical line from the end of the panel hits the table top, then measure back to the end of the panel and it comes to 38 cm, which is a. Now divide b/a = 22/38 = 0.579. Put this value into a cell and just to the right put = then go to the tool bar and click on MATH & TRIG, then select ATAN. Put in the cell coordinates and hit ENTER. You should get the value 0.52476 or something close to that. Now go one more cell to the right and type in = again then go back up to MATH & TRIG and select DEGREES. Put in the cell and hit ENTER. You should get 30.0665 degrees. That's how to calculate the angle that the solar panel makes with the table.

If you have more questions, just let us know.

Sybee