polarization of light



It is known that light is a transverse electromagnetic wave.Electromagnetic oscillations are carried out of the electric (E) and magnetic (H) fields.The electric field vector is called light.It determines the amount of energy transferred in the space.The intensity of the light depends on the module of this vector.

Each oscillates in a plane perpendicular to the wave propagation vector.If these fluctuations are carried in all directions (perpendicular to the plane is stored), the light is called unpolarized or natural.These light waves are emitted by the sun and all earthly sources.

Polarized light occurs when the passage of a wave of certain substances.Light vector begins to oscillate in a single plane that is perpendicular to the plane of the oscillations of the magnetic vec
tor and the vector direction of propagation.Such light is called linear or plane-polarized.To the human eye, he is no different from a natural, but using it can be observed interesting phenomena.

Act Malus



Get the plane-polarized light is possible by means of a crystal of tourmaline.In 1809, French engineer E.Malyus opened an interesting property of this light.In his experiments, he used two plates made of tourmaline.He placed the light source and the two plates on the optical bench.

Malus put a plate so that you can change the angle between them (it is formed of planes of polarization).The plate is located closer to the source, was called a polarizer, and one that more - analyzer.These names are conventional, as the records do not have quality differences.

When changing the angle of the intensity of the light transmitted through the analyzer change.If the planes of polarization are perpendicular, it was zero.Each plate "cut" certain plane of oscillation of the light vector, because of what changes the intensity of the light wave.

After a thorough analysis of the results was opened formula relating the intensity of plane-polarized light passing through the analyzer, the intensity of natural light.It looks like this: I = 0.5 * I0 * (cosF) ^ 2, where I - intensity of natural light, I0 - intensity of the light transmitted through the analyzer, F - the angle between the planes of polarization of tourmaline plates.