Permanent exhibitions

Light games

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The Exhibition

"Light games" is a reconfiguration of the exhibition "Looking at the light", designed by the Exploratorium of San Francisco and presented in 1987 to the Cité des Sciences et de l'Industrie.

With sparse decor and discreet lighting, this interactive and playful exhibition invites you to experiment with the phenomena of the physics of light. Alone or as a group, try out the sixty experiments divided into two large sections:

  • The first deals with the phenomena of reflection, refraction, diffraction and interference
  • The second looks at the perception of colour, how the eyes and vision work, and optical illusions based on incorrect interpretations by the brain.

In the exhibition, each experiment is accompanied by a user guide and an explanation of its scientific context.


© Cité des sciences et de l’industrie / J.P. Attal

1. Reflection, refraction, diffraction and interference

© CSI / S. Chivet

The experiments in the first section allow you to:

  • Test how reflection can multiply images infinitely, as well as move them, transform them and superimpose them on each other
  • Experiment with the principles of refraction and diffraction: when light travels through water, glass or air, it is refracted; when it crosses a block of plastic or glass, it changes direction; when it goes through a prism, it is broken down into rainbows; when refracted through lenses, it forms clear images
  • Observe the phenomena of interference (iridescence of petrol, soap bubbles, opals, etc.) which is produced when luminous waves gather together or separate, making the invisible visible.


Some astonishing experiments to be tested in this exhibition:

  • Multiply yourself: with a collection of mirrors angled at 60°, you can multiply your reflection infinitely!
  • The untouchable spring: have a go at touching the spring you can see! It seems so real that you'll find it hard to believe that it's only an image reflected by a concave mirror.
  • Return to sender: test your image reversed like in an ordinary mirror – with this reflector, you effectively see the reflection of a reflection of a reflection.
  • Broken finger: this experiment gives you the illusion of having a broken finger. This is due to the light being refracted through a plastic block, distorting the images.
  • Soap painting: press the button to get a layer of soap the size of a painting, then watch the changing colours and guess what colour it will be when the skin bursts.
  • Visualising sound: send vibrations through a metal tray sprinkled with fine sand using a bow, and watch the patterns created by the vibrations, which are normally invisible.

2. Colours, vision, illusions

© Cité des sciences et de l'industrie

The experiments in the second section encourage you to:

  • Test whether an object can emit light (bulb), transmit the light received more or less fully and faithfully (coloured filter) or reflect all or part of the light it receives
  • Experiment with our perception of depth, linked to the way our brain processes two slightly different images formed on the retina of each of our eyes. Learn about the optical illusion created by the brain when it processes the information using past experience.



Some astonishing experiments to be tested in this exhibition:


  • Light games: play with mirrors, lenses, prisms and light, and experiment with the mix of colours and the deviation of light.
  • Colours that disappear: study the combination of colours that make up white light using prisms and filters.
  • Bird in a cage: why do we see colours that don't exist? An experiment to test the residual images that stay on your retina.
  • Observe the corpuscles: watch the blood corpuscles move around inside your eye! These tiny shiny points that you see are due to light being diffracted by red blood corpuscles.
  • Two in one: with this experiment where you evaluate depth and perceive dimension, you can check the idea that your brain combines the perspectives of each of your eyes to show you a world in 3 dimensions.
  • Mask and anti-mask: move in front of these masks, one in relief and the other one indented. You'll get the strange feeling that the indented one is following you with its eyes!
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