Physics · Ch 6 — Optics
Plane Polarised Light
Plane Polarised Light
A transverse wave whose vibrations occur in every direction within the plane perpendicular to its propagation direction is called unpolarised light; these vibrations can always be resolved into two perpendicular components. If the vibrations of a wave are instead restricted to occur in only one direction within that perpendicular plane, the light is said to be polarised, or plane polarised. The plane containing the electric-field vibrations themselves is called the plane of vibration; the plane perpendicular to it (but still containing the ray direction) is called the plane of polarisation -- the two planes always share only the ray direction as their common line, and are otherwise mutually perpendicular. Polarised light is asymmetrical about the ray direction and can only be produced from unpolaris …
What this figure shows. Four small panels contrast unpolarised and polarised transverse waves. Panels (a) and (b) show unpolarised light: its electric field vector E is drawn pointing in every direction within the plane perpendicular to propagation, which can equally well be resolved into two perpendicular component directions, both present with equal average amplitude. Panels (c) and (d) show plane polarised light instead: the electric field vector E is drawn confined to a single fixed direction in that same perpendicular plane, with no component at all along the perpendicular direction -- the essent …
What this figure shows. For a beam of plane polarised light, the flat plane ABCD containing both the ray direction and the single fixed direction the electric field actually vibrates in is called the plane of vibration; a second flat plane EFGH, perpendicular to the plane of vibration but still containing the ray direction, is called the plane of polarisation -- the two planes are always mutually perpendicular, sharing only the ray direction its …
| S.No | Polarised light | Unpolarised light |
|---|---|---|
| 1 | Consists of waves having their electric field vibrations in a single plane normal to the direction of ray. | Consists of waves having their electric field vibrations equally distributed in all directions normal to the direction of ray. |
| 2 | Asymmetrical about the ray direction | Symmetrical about the ray direction |