5 Experiments to do with a Glass of Water

In this series of science experiments, kids explore light refraction using a glass of water.

Light is a disturbance of electric and magnetic fields; it travels in the form of a wave, just like sound.  Unlike sound, however, light does not have to have particles to bump in order to travel; light waves can travel through completely empty space -- unless something blocks it.

Transparent material, such as glass or clear plastic, allows light to pass straight through.  Translucent materal, such as waxed paper, allows some but not all light through.  Opaque materials, such as cardboard and tin foil, allow no light through at all.

Light always travels in a straight line, but sometimes the direction of the line changes.  For example, when a ray of light moves from air (a less dense substance) to water (a more dense substance), the light ray bends and changes direction.  This is called refraction, and it happens when light rays slow down or speed up. Refraction often creates optical illusions, such as making things look larger or split apart, as in the experiments demonstrated here.

A curved glass filled with water acts like a lens:  it both refracts the light (bends it), and at a certain distance, reverses the image being viewed. This happens when the light that is bent by the glass eventually comes together into a “focal point” – which is where you can see the object clearly – then comes out the other side crisscrossed, which makes the image look reversed.