How does light work? Making a water prism
How do we see color? In this activity students release the colors in the rainbow through the action of bending light in a water prism.
- You will need to do this outside or with the sunlight streaming through a window
- A bowl full of water
- A mirror
- A sheet of white paper
- Science notebook or lab sheet
- You may want to view the video ahead of time which shows how to move the paper to find the rainbow
- You may want to introduce your class to color and light with the Light and Color video
GBO suggestion - Do this activity as a station in a rotation with several other light activities.
Suggested GBO activities to create stations are:
- How does light work? Angles of reflection
- Making sense of color
- Set up your bowl of water where the light will hit it.
- Place the mirror in the water facing the light.
- Hold the piece of white paper in the reflected light to capture the rainbow. You may have to draw your paper outwards to find your rainbow.
- We advise you test your location before having students perform the activity.
- Have students complete the age appropriate Lab Sheet.
This experiment demonstrates light being refracted. Refraction is caused to the light waves when they enter a different substance, with a different density, causing the light waves to slow down or speed up. When natural light enters the water the wavelengths slow down and bend. Since white light is made up of different wavelengths, each wavelength bends at a different angle. Red light bends the least, while violet light bends the most. The mirror amplifies the bending effect, which allow one to capture the rainbow on the sheet of white paper.
Video on making a water prism (instructor may want to view before trying activity)
Bill Nye the Science Guy- great way to introduce light and color