Spinning Colors: How Do Primary Colors Combine to Make New Colors?
AbstractDid you know that sunlight can actually be separated into the colors of the rainbow? And the light of different colors can be added together to make white light or new colors. This is an area of study where art and science overlap. In this science fair project, you will explore this area by drawing or painting "pie slices" onto a white circle and then combining them to make a new color by spinning the wheel using an electric drill.
David B. Whyte, PhD, Science Buddies
The objective is to investigate how primary colors combine to make new colors.
Have you ever wondered from where all the beautiful colors that you see around you come? How are they made? It all starts with the three primary colors of light, which are red, green, and blue. When two primary colors of light are mixed together, a secondary color is created. For example, red and green light mix to make yellow light. If you mix all three colors of light—red, green, and blue—on a single spot on a screen, they form white light! This is called color addition. Color addition involves combining different colors of light to form a new color of light. The new color is made by adding colors of light together.
If you mix red and green paint, however, the mixture is closer to brown than it is to yellow. Why? This is because paint colors combine by color subtraction. Color subtraction is the process of absorbing certain colors. For example, red paint absorbs (subtracts) green light, and the green paint absorbs (subtracts) red light, so when you mix the red and green paint, the mixture becomes a muted drab color, close to brown. As more colors of paint are mixed in, more colors are subtracted, and the mixture becomes darker, eventually becoming black.
In this science fair project, you will add colored light together to determine what new colors can be formed. To do this, you will make a color wheel and attach it to a cordless drill. A red section on the wheel, for example, is seen as red because it reflects red light while absorbing other colors. When the wheel spins, the colors will add together to make a new color. If you have a red section and a yellow section on the drill, for example, these colors are added together by your brain and perceived as orange. This science fair project will provide you with a lot of opportunities to experiment with the creation of new colors by color addition!
Terms and Concepts
- Primary colors
- Secondary colors
- Color addition
- Color subtraction
- Based on your research, what color is formed when blue and green light are added?
- What are the colors of the rainbow? Hint: the first letters of the colors form the name Roy G. Biv.
- Based on your research, what colors are filtered out (subtracted) by blue paint?
- Do your television and computer screens use additive or subtractive colors to make images?
Materials and Equipment
- White paper
- Metric ruler
- Colored markers, or paint and a paintbrush
- Glue or glue stick
- Cordless drill; available at your local hardware store
- Sanding disk; available at your local hardware store
- Drawing compass
- Safety goggles, available online from suppliers such as Carolina Biological Supply Company
- Lab notebook
- Adult helper
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- Draw a circle on the cardboard, using the sanding disk as a guide.
- Cut out the cardboard circle with the scissors.
- Draw a circle on the white paper, using the sanding disk as a guide.
- Divide the circle on the white paper into two halves.
- Color the two halves. Make one red and one blue.
- Cut out the colored circle.
- Glue the colored circle onto the piece of cardboard.
Attach the cardboard with the colored circle onto the sanding disk.
- The method for attaching the circle will depend on the type of drill.
- It might be helpful to glue the colored circle to a piece of sandpaper that fits on the disk. See Figure 1.
Figure 1. Cordless electric drill with sanding disk. This sanding disk has a Velcro-like surface to which round pieces of sandpaper attach.
Have your adult helper turn on the drill, which will spin the disk, as you look at it. What color do you see?
- Use caution when the drill is on.
- Do this in a brightly lit area.
- Caution: Be sure to wear your safety goggles and do not touch the spinning disk.
- Repeat the above procedure with other primary color combinations: red and green, blue and red.
Write your results in a data table in your lab notebook. The percentages represent the sections of the circle. For instance, 50% means that color takes up half of the circle.
Trial 1 Red Green Blue Result 50% 50% 0% 50% 0% 50% 0% 50% 50%
- Repeat steps 9–11 two more times, for a total of three trials. This will ensure your results are accurate and repeatable.
- Remove the two-colored disk. Now make a colored disk that is divided into three equal sections.
- Color the three sections red, green, and blue.
Repeat step 9. What color do you see?
- Since the colors are not likely to be pure and of equal darkness, you will probably have to vary the sizes of sections to get white. Be patient and keep trying.
Record your observations in your lab notebook. In the example data table below, you can see that each color is represented by 33%, which means one-third of the circle. Have an adult help you modify these numbers as you change the sizes of the color sections to get white.
Trial 1 Red Green Blue Result 33% 33% 33%
- Repeat steps 15–16 two more times, for a total of three trials. This will ensure your results are accurate and repeatable.
Ask an Expert
- Try to make other colors (peach, lime, navy blue, pink, etc.) by color addition, and record your observations in your lab notebook. Change the size of the pie segments, as needed. You can use black and white segments too. Record the data (colors added, segments sizes, resulting color) in your lab notebook.
If you like this project, you might enjoy exploring these related careers: