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Red car goes black experiment

You will need:

  • 1 Strong Torch and rubber band.
  • Green Cellophane
  • 1 Red object e.g. car, tomato, hat
  • A very dark room



  1. Place the green cellophane over the torch and secure with a rubber band.
  2. Darken the room and shine the green light on the red object.
  3. What colour do you see?
  4. Try different coloured objects and lights. Is the effect always the same?
  5. This science experiment works very well if you have access to a green spotlight
red car in white light
Red care under normal white light

red car in green light
Red car under pure green light

What is going on?

White light is comprised of all of the colours of the rainbow i.e. the light spectrum - visible light ranges in frequency from VIOLET (400nm) to RED (700nm). 

Different materials absorb and reflect the different colours of light. The different colours represent different wavelengths of light. A red object is only 'red' when you see the red wavelength of light being reflected off it. So a red car reflects red light, while the other light wavelengths get absorbed. The green light from your torch does not have a red wavelength in it. Because the red car only absorbs green light, no light is reflected and you are left seeing a black car.

Find out more on light through the external link Museum Victoria.

Be Amazing Book Front Cover; Ben Newsome, teacher & founder of Fizzics Education. Be Amazing -how to teach science the way primary kids love
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