Science Buddies: "Ask an Expert"

I read in a previous post about the type of bulb needed for the "How Does Color Affect Heating by the Absorption of Light?" project, that one should use a 250 W heat lamp bulb with a red filter. I was concerned about the red filter so I did some searches online to find out the purpose of the red filter. Apparently, the red filter reduces the amount of visible light emitted by the bulb. So I have a few questions about this...

1) Is the 250 W heat lamp bulb with a red filter what I actually should use in this experiment?
2) If the answer to question 1 is yes, I thought the purpose of this project is for the jar of water to absorb light (which is then converted to heat and then causes temperature rise in the water) and not necessarily to absorb the heat generated by the bulb? Doesn't using a red filter (which reduces visible light emission) defeat that purpose?
3) If the answer to question 1 is no, what type of bulb should I use? 250 W heat lamp bulb with no filter (clear)? Other?
4) This may be a dumb question and I apologize if it is, but doesn't using a red filter make the white incandescent light (presence of all colors) a red incandescent light (only red wavelengths) and then there's no other wavelengths of light for the construction paper to absorb or reflect other than red?

Thanks in advance for your advice.

This looks like a fun project! I haven't personally done it but as I read through the procedure and materials list I don't think there is a specific reason for the red filter - I think it's just the type of bulb that is readily available in heat lamps.

You are correct that using a red filter will remove the red visible light. Since less light will be making it's way to your jars it could effect how much they absorb. Maybe you can test in your experiment if a clear bulb heats the jars more efficiently than a red bulb? Does the color of the bulb combined with the color of the construction paper make a difference (i.e. red bulb + red paper)? Given the wavelength of red light would you expect it has higher or lower energy than the rest of the spectrum being emitted from the bulb?

Good luck and have fun!

Audrey