Unpolarzied to polarized light

In summary, when unpolarized light of intensity Io passes through a Polaroid sheet with its polarizing axis at the 12 o'clock position and then through a second sheet with its polarizing axis at the 1 o'clock position, the intensity of the emerging light is given by I= Io * 0.5 * cos2(30). This is because the unpolarized light is equally likely to have components aligned with the filter direction and at right angles, resulting in half the intensity getting through. The angle between the 12 o'clock and 1 o'clock filters is 30 degrees, as 1 o'clock is 1/3 of the way between 12 o'clock and 3 o'clock on a clock face
  • #1
superslow991
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Homework Statement



Unpolarized light of intensity Io passed through a Polaroid sheet with its polarizing axis at the 12 o'clock position and then through a second with its polarizing axis at the 1 o'clock position. What is the intensity of the emerging light?

Homework Equations


[/B]
I= I0 *0.5*cos2(30)

The Attempt at a Solution


Now i know the solution i just want a break down of the question. Why is it that when a unpolarized light passed through a polaroid, it loses 1/2 its intensity?

Also where would the 30 degrees come from? Also is it possible to draw this question out?
 
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  • #2
Intuitively, the factor of 0.5 is because the unpolarized light is exactly as likely to have components aligned with the filter direction as at right angles. So half the light intensity gets through. You can probably do a little trig and calculus to calculate the 0.5. The cos(30) is due to the angle between the first filter at 12 o'clock and the second filter at 1 o'clock.
 
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  • #3
FactChecker said:
Intuitively, the factor of 0.5 is because the unpolarized light is exactly as likely to have components aligned with the filter direction as at right angles. So half the light intensity gets through. You can probably do a little trig and calculus to calculate the 0.5. The cos(30) is due to the angle between the first filter at 12 o'clock and the second filter at 1 o'clock.

Hmm how can you be sure that the angle between the 12 o clock filter and 1 o clock filter is 30 degrees though?
 
  • #4
superslow991 said:
Hmm how can you be sure that the angle between the 12 o clock filter and 1 o clock filter is 30 degrees though?
12 o'clock is straight up and 3 o'clock is horizontal so that is 90°. So 1 o'clock is 1/3 * 90° = 30°
 
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  • #5
FactChecker said:
12 o'clock is straight up and 3 o'clock is horizontal so that is 90°. So 1 o'clock is 1/3 * 90° = 30°
ok thanks a lot
 

What is unpolarized light?

Unpolarized light is a type of light that does not have a specific direction of oscillation. This means that the electric and magnetic fields of the light waves have random orientations and can vibrate in any direction perpendicular to the direction of travel.

What is polarized light?

Polarized light is a type of light that has a specific direction of oscillation. This means that the electric and magnetic fields of the light waves vibrate in a single plane, perpendicular to the direction of travel.

How is unpolarized light converted to polarized light?

Unpolarized light can be converted to polarized light through a process called polarization. This involves passing the unpolarized light through a polarizing filter, which only allows light waves with a specific direction of oscillation to pass through. The resulting light is polarized.

What is the purpose of polarized light?

Polarized light has various uses in different fields, including photography, 3D movie technology, and LCD screens. In scientific research, polarized light is often used to study the properties of materials, as the way the light waves interact with the material can provide valuable information about its structure and composition.

Can polarized light be converted back to unpolarized light?

Yes, polarized light can be converted back to unpolarized light by passing it through a second polarizing filter with a perpendicular orientation to the first filter. This process is known as depolarization and results in the light waves becoming randomly oriented again.

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