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Slide from ultraviolet through the rainbow to infrared. Which light makes the star glow?
Rainbow and Beyond lab · Last updated: 16 October 2026
You slide a control from ultraviolet, through every colour of the rainbow, to infrared, and watch what happens in the scene. The colours we see turn out to be a small slice of a much wider family of light.
What you'll discover
- Visible light is only a narrow band in a much bigger range called the electromagnetic spectrum.
- Ultraviolet has shorter waves than violet light; infrared has longer waves than red.
- Some materials glow with visible light when ultraviolet shines on them.
The science in plain words
Light is a wave of electric and magnetic fields travelling through space. Different colours have different wavelengths. Red light has the longest waves we can see, about 700 billionths of a metre, and violet the shortest, about 400 billionths.
The full family is called the electromagnetic spectrum. Beyond violet are ultraviolet, X-rays and gamma rays, with ever shorter waves and more energy. Beyond red are infrared, microwaves and radio waves, with ever longer waves. All of them travel at the same speed in space, about 300,000 kilometres per second.
Our eyes only detect the narrow visible band, but other kinds of light have effects we can notice. Infrared is given off by warm objects, which is why we feel the warmth of a fire and why thermal cameras can see people in the dark. Ultraviolet from the Sun causes sunburn. Some materials absorb ultraviolet and give off visible light, which is called fluorescence; that is why highlighter ink and some minerals glow under an ultraviolet lamp.
Radios, mobile phones, microwave ovens, TV remotes and hospital X-rays all use different parts of this same spectrum.
Where it fits
- India, NCERT: The full electromagnetic spectrum goes beyond the NCERT syllabus for classes 6 to 10; the lab builds on the spectrum of white light in Class 10 Chapter 10: The Human Eye and the Colourful World.
- United States: Grades 9 to 12
Common questions
What is the electromagnetic spectrum?
It is the whole range of electromagnetic waves, from radio waves with very long wavelengths, through microwaves, infrared, visible light and ultraviolet, to X-rays and gamma rays with very short ones.
Why can't we see ultraviolet or infrared light?
Our eyes have cells that respond only to wavelengths from roughly 400 to 700 billionths of a metre. Ultraviolet waves are shorter and infrared waves longer, so our eyes do not detect them.
Why do some things glow under ultraviolet light?
Some materials absorb invisible ultraviolet light and give off some of that energy as visible light. This is called fluorescence, and it is why highlighter ink glows under an ultraviolet lamp.
Related labs
- Prism Rainbow: Split white light into a rainbow with a glass prism.
- Radio Mast to House: Send radio waves across town. How fast do they arrive, and why is the far house quieter?
- Greenhouse Effect: How does a little CO₂ in the air keep the whole planet warmer?
See all physics labs or every Taz science lab.
Try it yourself
The Rainbow and Beyond lab is one of the interactive 3D science labs inside Taz. Change one thing, predict what will happen, then run it and watch. Labs open after you sign in.