Bottle lens

Stunning optical illusions with a bottle of water!

10 minutes


  • Carefully review the general safety advice on the back of the box cover before starting the experiment.
  • Never leave lenses exposed to direct sunlight; this is a fire hazard.

Step-by-step instructions

Fill a plastic bottle with water. Now you have a cylindrical lens!


Look at the picture through the lens. Try adjusting the distance between your eyes and the lens and see what happens!


Explore the world through the lens!


Did you know that cylindrical lenses are also used in theaters? Lenses stretch images horizontally so there is no blank space on the sides of the screen.



  • Dispose of solid waste together with household garbage.

Scientific description

It's amazing how many unusual yet simple physics phenomena surround us in everyday life. Take lenses, for example—they’re everywhere: a glass, a plastic water bottle, and even a drop of water. Lenses—transparent rounded objects that change the direction of light rays—have a wide field of applications: from magnifying glasses and ordinary glasses to cameras and telescopes!

How does a bottle of water reverse an image? Let’s follow the path of the light, which, depending on your lighting conditions, originates from the Sun or a light bulb. Light hits the image and is mainly reflected from it. The reflected rays pass through the bottle of water and reach our eyes. At what moment in the journey does the image flip? The rays emanating from any particular point of the drawing are collected behind the cylinder, and the image is inverted due to the refraction of the rays on the cylinder, creating the reversed replica you see.