Polarizer is a device used for obtaining polarized light. Two polarizers can give an eclipse effect.
Light is an electromagnetic wave. If that wave oscillates in one plane, it’s called linearly polarized. Light can become polarized by passing through an object or reflecting from its surface. Polarizers presented here filter only linearly polarized light. If the polarizers are set in such a relation to each other so that they pass the light wave in a single plane, we can see a clear image. If the planes are perpendicular to each other – an eclipse occurs.
There are two polarizers for you to use. Look through the first polarizer while turning the knob. Set both polarizers in such positions so that they pass the light. Then turn the knob and watch the eclipses occur.