Measuring brightness of sun print paper image?

[lloviendoamor]

I found my science fair project using the science buddies website. It's called: Colorful Chemistry Creations: Make Your Own Sun Print with Color and Sunlight! Here's the URL: http://www.sciencebuddies.org/science-f ... p084.shtml

Basically, I using colored sharpies and sun print paper, i'm trying to figure out how different colors of light affect the brightness of a sun print paper image. The more light an object lets in, the weaker the image on the sun print paper is. I need to produce a table and a graph for my data, but I'm not sure how i'm supposed to measure the brightness of an image. I could use observation and comparison but how do I display that on a table or graph?

HELP! MY PROJECT IS DUE IN A FEW DAYS!!!

[wendellwiggins]

Hello lloviendoamor,

If you have access to a photometer, it would give you a quantitative measure of brightness. If you don't have one, a secondary method would be to compare the brightness of the image to some reference paper. The instructions in the experiment say to just rank the brightnesses you get from bright to dark in order. This tells you the relative brightness, but nothing about the quantitative brightness.

You can make your own reference as follows. Cut a sheet of the sensitive paper into strips. Label each strip with an exposure time and expose each strip for the labeled time. Develop all the strips. The total intensity of light each one was exposed to is proportional to the exposure time. Now compare your other images to these reference strips to find out which reference strip matches each of your other images.

Good luck, WW

[lloviendoamor]

Thank you so much! Unfortunately, I don't have access to a photometer but doing the strips is an excellent idea. Is there any other way I could get quantitative data for my table and graphs? I don't think my teachers would let me turn in my project with tables and graphs based off of qualitative data, would they? Is there some sort of photometer online perhaps?

[wendellwiggins]

lloviendoamor,

You can buy photometers online, but unless you get one that can focus on a small area of your exposed paper and ignore the surrounding light, it won't be accurate. Given your short time, the expense, and the simplicity of the exposed paper strips, I suggest that you stick with that method.

WW