How do I see colour?
How does this align with my curriculum?
How is light connected to the colours we see? In this STEAM activity make a colourful light catcher and discover why we see different colours?
What You Need
- Styrofoam plates or trays (like those in which some vegetables or fruits are sold)
- Clear acetate or other clear plastic sheet
- Permanent markers
- Tape
- Scissors
- Small cookie cutters
- String or yarn
- Hole punch or a sharp pencil
Safety First!
Some plastics are difficult to cut. Ask an adult for help if sharp scissors are needed.
What To Do
- Cut the edges off a Styrofoam plate or tray so that you have a flat surface.
- Create holes in the Styrofoam flat surface with the small cookie cutters.
- Cut pieces of acetate large enough to cover the holes made with the cookie cutters, and colour them with markers of various colours.
- Tape the coloured pieces of acetate behind the openings in the Styrofoam.
- Punch a hole near the top of the piece of Styrofoam using a hole punch or a sharp pencil. Put a string or piece of yarn through and knot it so that it makes a loop.
- Hang the sun catcher in a sunny spot or attach it to a window.
Discovery
White light from the sun is made up of different colours. When you look at a rainbow, you can see white sunlight broken up into its components as a beautiful colour spectrum of red, orange, yellow, green, blue, indigo and violet. By using a filter such as the pieces of coloured acetate, you allow only light of a certain colour to pass through it. For example, if you coloured one of the pieces of acetate blue, you are only allowing the blue light rays to go through it. The filter will absorb all other colours of white light.
Light is required for colour to exist. When white light hits an object that appears red, for instance, that object absorbs all the rays of coloured light except the red ones, which it reflects. When our eyes perceive the reflected light rays, they send a signal to our brain which will interpret what we are seeing as the colour red.
The back of our eye balls are covered in light-sensitive cells. Some transmit information about colours to the brain and some transmit only black and white information. The cells that perceive colours are not as sensitive as the others, making it much harder to see distinct colours in places where there is not a lot of light (like at dusk or in a dimly lighted room).
- Shine a flashlight on a glass or Plexiglas triangular prism and see how light is split into the colours of the visible spectrum (red, orange, yellow, green, blue, indigo and violet). You could also use a crystal pendant from a chandelier to see what happens to the light that passes through it. Be sure to aim the light passing through the prism towards a white wall or white surface to best see the light spectrum. (Note that this will not work if your flashlight has an LED lightbulb.)
For more information on this topic check out these Let's Talk Science resources:
- Is a green apple always green? (Hands-on Activities) - What does light have to do with colour? Observe some colourful fruit under different conditions to learn why we see the colours we see!
- How do we see colour? (STEM in Context) - How does the human eye see visible light as colour? And why do some people see more colours than others?
- What is white light? (Hand-on Activities) - Find out what happens if you spin the colours of the rainbow in this hands-on activity.
- How We See (Backgrounder) - Learn about how human vision works as well as some common types of vision problems.
What’s happening?
White light from the sun is made up of different colours. When you look at a rainbow, you can see white sunlight broken up into its components as a beautiful colour spectrum of red, orange, yellow, green, blue, indigo and violet. By using a filter such as the pieces of coloured acetate, you allow only light of a certain colour to pass through it. For example, if you coloured one of the pieces of acetate blue, you are only allowing the blue light rays to go through it. The filter will absorb all other colours of white light.
Why does it matter?
Light is required for colour to exist. When white light hits an object that appears red, for instance, that object absorbs all the rays of coloured light except the red ones, which it reflects. When our eyes perceive the reflected light rays, they send a signal to our brain which will interpret what we are seeing as the colour red.
The back of our eye balls are covered in light-sensitive cells. Some transmit information about colours to the brain and some transmit only black and white information. The cells that perceive colours are not as sensitive as the others, making it much harder to see distinct colours in places where there is not a lot of light (like at dusk or in a dimly lighted room).
Investigate further
- Shine a flashlight on a glass or Plexiglas triangular prism and see how light is split into the colours of the visible spectrum (red, orange, yellow, green, blue, indigo and violet). You could also use a crystal pendant from a chandelier to see what happens to the light that passes through it. Be sure to aim the light passing through the prism towards a white wall or white surface to best see the light spectrum. (Note that this will not work if your flashlight has an LED lightbulb.)
For more information on this topic check out these Let's Talk Science resources:
- Is a green apple always green? (Hands-on Activities) - What does light have to do with colour? Observe some colourful fruit under different conditions to learn why we see the colours we see!
- How do we see colour? (STEM in Context) - How does the human eye see visible light as colour? And why do some people see more colours than others?
- What is white light? (Hand-on Activities) - Find out what happens if you spin the colours of the rainbow in this hands-on activity.
- How We See (Backgrounder) - Learn about how human vision works as well as some common types of vision problems.