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3 experiments with light

Professor Philippe Smet of Ghent University (Faculty of Science, Department of Solid-State Sciences) shows how to trap light yourself, why the sky is blue and how to build a spectroscope.

How can you make light change direction?

Philippe shows you how you can trap a beam of light from a laser pointer or a bicycle lamp in a simple jet of water. If you succeed, then you will understand how light travels in the glass fiber cables used for high-speed internet and other things.

How can you see which colors are present in light?

Make your own spectroscope from a simple cardboard tube and an old CD. Aim your spectroscope at a fluorescent lamp, an LED lamp, an old bulb or a fire and find out what colors these light sources are made of! Did you know that astronomers use just such a device - only a little bit more complicated - to analyze the light of stars and galaxies?

Why is the sky blue and the clouds white?

In space, when you look at the sun, it looks white. Here on Earth, under the atmosphere, it is yellow, and even orange-red at night. The blue light is gone, scattered across the sky. With water, milk and a LED bicycle light we can recreate this effect ourselves!

Ghent University

This article was produced in collaboration with Ghent University, partner of Lichtfestival Gent. Read more fascinating stories about Ghent University research on