The Color Vision simulation from PhET lets you make a whole rainbow by mixing red, green and blue light. You can change the wavelength of a single-color beam, pass white light through colored filters, and view light as a beam or as separate photons. It is free, runs in any browser on a phone, tablet or laptop, and it is a great fit for the light and colour lessons in Tamil Nadu State Board (Samacheer Kalvi) Science and Physics.
What is the Color Vision simulation?
This interactive simulation lets you explore how we see color. You can mix red, green and blue light, change the wavelength of a monochromatic beam, or filter white light, and you can look at the light as a solid beam or as individual photons. Because it runs on HTML5, there is nothing to install, and it works on phones, tablets, Chromebooks and computers.
Elementary to university
Light, color mixing, filters and photons
Phone, tablet, Chromebook, PC
English
PhET’s learning goals are to work out what color a person sees under different combinations of red, green and blue light, and to describe the color of light that can pass through different colored filters.
Launch the Color Vision simulation online
Tap or click inside the player and start exploring. Use the full-screen button in the player for a bigger view.
Credit: University of Colorado Boulder
How to use the Color Vision simulation, step by step
- Predict first. Before you turn on any light, say what color you expect to see.
- Mix the lights. Combine red, green and blue light in different ways and note the color you see.
- Change the wavelength. Use a single-color (monochromatic) beam and change its wavelength to see the rainbow of colors.
- Try the filters. Shine white light through colored filters and see which colors pass through.
- Switch the view. Compare the solid beam view with the photon view.
Tip for students: write down each combination and the color you see. A table of your results makes the pattern easy to spot.
The idea behind the simulation: adding light
Red + Green + Blue = White
Light mixes by adding. Red, green and blue are the three primary colors of light. Red and green make yellow, red and blue make magenta, and green and blue make cyan. All three together make white, and no light at all looks black. A colored filter works the other way: it lets only its own color pass through and blocks the others.
Worked example: Red light plus green light looks yellow to your eyes. If you shine white light (red + green + blue) through a red filter, only the red part passes, so you see red light.
Light and color key terms explained
These are the words you will meet while using the Color Vision simulation, with simple meanings.
Primary colors of light
Red, green and blue. Mixing them in different amounts makes other colors.
White light
Light that contains all the colors of the spectrum.
Monochromatic light
Light of a single color, which means a single wavelength.
Wavelength
The distance between two peaks of a light wave, measured in nanometres (nm). Each color has its own wavelength.
Photon
A tiny packet of light energy.
Spectrum
The band of colors that white light splits into, like a rainbow.
Filter
A colored sheet that lets some colors of light pass and blocks the rest.
Additive mixing
Making new colors by adding lights together.
Common mistakes: Mixing up light mixing with paint mixing, thinking a filter adds color to the light instead of blocking the other colors, and believing that white light has no color.
Try the light color mixer (practice what you explore)
Move the sliders to set how bright each light is, from 0 to 100. The mixer shows the color you would see. Then tap a “what if” button.
What happens when you change a variable
| Change | Effect |
|---|---|
| Red + green light | Yellow |
| Red + blue light | Magenta |
| Green + blue light | Cyan |
| Red + green + blue light | White |
| White light through a red filter | Only red light passes |
| Dim all lights equally | The color gets darker, then black |
Classroom activities for teachers
The Color Vision simulation fits a single 40-minute period.
- Predict and test (10 min): students predict the color of each light mix, then check it in the simulation.
- Mixing table (10 min): students fill in a table of all the red, green and blue combinations.
- Filter challenge (10 min): students predict which colors pass through each filter and test their ideas.
- Exit ticket (10 min): students explain in two sentences why a red filter makes white light look red.
Looking for the matching chapters? Browse the Science and Physics books on TN SchoolBooks and download the Samacheer Kalvi PDFs, then use this simulation to make the light and color lessons visual. More free science simulations and textbook PDFs are on the home page.
Quick quiz: test your understanding of color
Score: 0 / 5
Color Vision simulation: frequently asked questions
Is the Color Vision simulation free?
Yes. PhET simulations are free to run online in a browser. Check PhET’s licensing page for reuse terms.
Does it work on a mobile phone?
Yes. It is built with HTML5 and works on phones, tablets and Chromebooks. Use landscape mode or the player’s full-screen button for a bigger view.
What are the primary colors of light?
The primary colors of light are red, green and blue. Mixing them in different amounts makes all the other colors, and mixing all three equally makes white.
Why is mixing light different from mixing paint?
Light mixes by adding, so more light makes a brighter color. Paint mixes by taking away (absorbing) colors, so mixing more paints makes a darker color.
The Color Vision simulation turns the colors you see every day into something you can mix, filter and understand. Explore it, take the quiz above, and keep experimenting until predicting the color feels easy.