Question

Sun glasses are made of polaroid’s and not of coloured glasses, why? Give examples for two commonly used devices which make use of polarised light.

Answer 1

Hint: We know that while all scattered light is polarized to some extent, light is highly polarized at a scattering angle of[ $90{}^\circ$ from the light source. In most cases the light source is the sun, but the moon creates the same pattern as well. Thus, the maximum degree of polarization occurs in a circular band 90° from the sun. Circularly polarized electromagnetic waves are composed of photons with only one type of spin, either right- or left-hand. Linearly polarized waves consist of photons that are in a superposition of right and left circularly polarized states, with equal amplitude and phases synchronized to give oscillation in a plane.

Complete step by step answer
We can say that polarized light waves are light waves in which the vibrations occur in a single plane. The process of transforming unpolarized light into polarized light is known as polarization. Plane polarized light: Light whose electric field oscillates in just one plane. Non Polarized light. Electric field oscillates in all directions. Polarizer. Object which causes polarization.
Sunlight is being considered as a source of unpolarized light. So, goggles made of Polaroids will reduce the intensity of the transmitted light and make you feel comfortable which coloured glass does not and hence are more suitable than coloured glasses. Commonly used devices which make use of polarized light are, Linear and circular polarizer, phase plate, optical compensators and depolarize. These are simple devices used for production and conversion of polarized light.

Note it can be said that only transverse waves can be polarised. Longitudinal waves cannot be polarised. Transverse: vibrations perpendicular to the direction of travel of the wave. Longitudinal: vibrations parallel to the direction of travel of the wave. When light shines from the sun or moon, molecules in Earth's atmosphere tend to make a lot of these light waves lineup so they vibrate together in the same direction. The light is then said to be polarized.