Polarisation

Also called

polarization · polaroid · polariser · analyser · Malus's law · crossed polaroids · plane polarised light · unpolarised light · Brewster's angle · polarisation by reflection · glare · polaroid sunglasses · transverse wave · pass axis · wave optics · ध्रुवण · ध्रुवित प्रकाश · ब्रूस्टर कोण

Topics

• Light is a transverse wave: its electric field vibrates at right angles to the direction it travels.
• Ordinary light is unpolarised: across the beam the vibrations point in every direction.
• A polaroid passes only the vibrations along its pass axis; the light leaving it is plane polarised.
• Unpolarised light loses half its intensity through one polaroid, whichever way the polaroid is turned.
• Malus's law: a second polaroid at angle θ to the first transmits I = I₀ cos²θ; crossed (θ = 90°) it passes nothing.
• Light reflected from water or glass is partly polarised parallel to the surface…
• At Brewster's angle iB (tan iB = n, about 53° for water) the reflected light is completely polarised.
• At Brewster's angle the reflected and refracted rays are at right angles to each other.
• Only transverse waves can be polarised; sound, a longitudinal wave, cannot.

About this model

A GLB file of about 280 KB, shown in Lably's 3D viewer and, on a phone, placed in your room with AR. Credit: Model, science and animation: Lably (built procedurally with three.js; no downloaded meshes). | CC BY 4.0. Original geometry and animation made for Lably.

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