What are the main difference between unpolarised light and linearly polarised light?

Answer 1

Light is the visible spectrum of electro-magnetic forces. Like all EM forces, its quanta (the photons) travel in transverse waves...like water molecules in the ripples on a pond. Transverse waves have their amplitudes in directions perpendicular to the direction the photons are traveling...sort of like the crests and valleys of those ripples on the pond going up and down while the ripples spread outward across the surface.

However, unlike the ripples that are confined to move up and down only, the transverse waves of light can and are oriented 360 degrees around the direction of photon travel. If you look down the direction of travel of a beam of light, the transverse waves from that beam would totally encircle the axis of that beam. When these transverse waves of light are oriented completely around the direction of the light, we call that "unpolarized" light.

This is of course a misnomer. In fact that kind of light is omni polarized...it is polarized in all (omni) angles around the light beam. But if we pass the omni poloarized beam through a linearly polarized piece of glass (your sun glasses for example), all but the transverse waves oriented in the same angle as the glass will be blocked out. There will be but one angle of transverse waves around the beam allowed through the glass. And that's the linearly polarized light.

Polarized sun glasses (like Ray Bans) block out all but the one orientation of the transverse waves. What would happen if you took another pair of Ray Bans and put it in front of the first pair, but oriented 90 degs to that first pair? Try it if you have two pairs of polarized sun glasses. I think you'll find that virtually all the sun light will be blocked out. This results because the second pair cuts out that one remaining orientation of transverse waves passing through the first pair.

Now rotate the second pair of glass around to make them oriented the same way as the first pair. The light will pass through again...why, because now both pairs are allowing the transverse waves that have that same orientation through both glasses. If you rotate the second pair back and forth in front of the first pair, you'll see the sun alternately come through, fade out to black, and come back again as their two linearly polarized light beams align with and part from each other.

Answer 2

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Answer 3

linearly polarized lite vibrates in only one direction..unpolarized lite vibates in all directions...done by passin lite thru polarizer like nicol prism