physics lab color



Watch the tutorial on Color at The Physics Place. (You should NOT be asked to login to access this site. If you have any problems, please contact Heather Hill via email.)



Swirls of Color (9 points)

Purpose: To separate light into colors.

Materials: bowl of water (1 quart or 1 liter); bottle of clear fingernail polish


  • Place the bowl of water on a table away from direct lighting.
  • Hold the brush from the polish bottle over the bowl of water and allow one drop of liquid polish to fall into the bowl.
  • Watch the surface of the water. Move your head so that you see the surface from different angles.


  1. What did you see?
  2. Why?
  3. Define spectrum.


Written Response (21 points)

First explain what the additive method is and use an example to illustrate this method (#1 below). Second explain what the subtractive method is and use an example to illustrate this method (#2 below). Finally, answer the set of questions that walk through how mixing red paint with green paint makes a brown or black color using the additive method of light reflection (#3 – 7 below).

  1. Additive Method (with an example):
  2. Subtractive Method (with an example):
  3. Why is red paint red?
  4. Why is green paint green?
  5. What will green paint do to the red light reflecting off the red paint?
  6. What will red paint do to the green light reflecting off the green paint?
  7. So, what will happen when red and green paint mix?

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