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# The Polarization of Light

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Two pieces of Polaroid are held against the light.

Can you look through them by themselves?

When they are stacked on top of each other?

What happens if you rotate one of the Polaroids while keeping the other one fixed. Explain why you observe a variation in transmitted light intensity.

https://brainmass.com/physics/electricity-magnetism/polarization-light-234785

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light rays

Two pieces of Polaroid are held against the light.

Can you look through them by themselves?

In longitudinal waves the vibrations of the medium are parallel to wave propagation and thus the vibrations are exactly similar in all planes drawn through the direction of propagation and hence we can say that the longitudinal waves are practically symmetrical about the direction of propagation.
In transverse waves the particles of medium vibrates perpendicular to the direction of wave propagation and thus are not symmetrical about direction of propagation.
Light is electromagnetic wave with variation of electric and magnetic field perpendicular to each other and both are perpendicular to the direction of propagation of light and hence transverse wave.
In normal light different wave pulses are distributed in such a way that we get vibration of fields in all direction and hence appears symmetrical with the direction of propagation. Such light is called un-polarized light.
Here we will consider only electric field as both fields are interdependent so magnetic field will always be perpendicular to it.
A simple Polaroid is a crystal (Tourmaline) which allows the field only in one direction which is parallel to its axis. Thus if normal light is passed through the crystal, the oscillations of the field in the direction perpendicular to the axis of the crystal are not allowed and the emerging beam will have oscillations only in the direction parallel to the crystal. In this beam the oscillations are not symmetrical about the direction of propagation and is called plane polarized light.
As the eye is incapable to detect the polarization only the decrease in intensity of light is observed.
Thus if we see through the two Polaroid we can see through them. They appear transparent and the intensity is decreased.

When they are stacked on top of each other?

When the two Polaroid stacked on top of each other in such a way that their axes are parallel, still we can see through them because the plane polarized light from one is having oscillations in the same direction as the axis of the other and it will allow them to pass through it. The group is still transparent.

What happens if you rotate one of the polarizers while keeping the other one fixed. Explain why you observe a variation in transmitted light intensity.
If the axes of the two Polaroid are not parallel, one is giving plane polarized light which is having field oscillations parallel to its axis but the axis of the other is not parallel to the oscillations and thus the component of the field in the direction of the axis of the other is allowed. Thus the allowed is less in magnitude which is further decreasing with angle. When the angle between the two axes is 900 component of the polarized light from first Polaroid is zero in the perpendicular direction and hence no light will pass through the second one and the system becomes opaque.
Hence the intensity of light emerging from the stack of the two is maximum when their axis are parallel, decreases with increase in angle between the axes and becomes zero when the axes are perpendicular to each other.

This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!