Polarisation of light refers to the orientation of the electric field of a light wave. Light is an electromagnetic wave, and the electric field component of the wave can oscillate in any direction perpendicular to the direction of propagation. Polarisation is the process of restricting the electric field to only one specific direction.
Polarisation can occur through various methods such as reflection, refraction, scattering, or passing through certain materials. When light is reflected or refracted at a certain angle, the electric field of the wave is restricted to a specific direction, resulting in polarisation. Certain materials, such as polarising filters, can also selectively block or transmit light waves based on their polarisation direction.
Polarisation of light has several important applications in various fields, including photography, LCD screens, 3D movies, and optical communication. Polarising filters are commonly used in photography to reduce glare and improve image quality. In LCD screens, polarisation is used to control the amount of light passing through the screen to create images. In 3D movies, polarisation is used to create the illusion of depth. In optical communication, polarisation is used to transmit signals through fibre optic cables.
Yes, polarisation can be reversed through the same methods that cause it, such as reflection and refraction. For example, if light is polarised through reflection at a certain angle, it can be depolarised by reflecting it at the same angle again. However, in some cases, polarisation cannot be reversed, such as when light passes through certain materials that selectively absorb certain polarisations.
Polarisation can be measured using a polarimeter, which is a scientific instrument that measures the degree and angle of polarisation in light. This instrument works by passing light through a polarising filter and then rotating the filter until the light is completely blocked. The angle of rotation of the filter can then be measured, which indicates the polarisation angle of the light.