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.