Intensity of light through two polarizers and Malus's Law

In summary, the conversation discusses the intensity of light passing through two polarizers with perpendicular transmission axes. The final intensity, according to Malus's Law, is 0.25 times the initial intensity if the incident beam is unpolarized. However, if the incident beam is already polarized, no light will pass through the second polarizer and the final intensity will be 0.
  • #1
Linus Pauling
190
0
1. A beam of unpolarized light with intensity I_0 falls first upon a polarizer with transmission axis theta1 then upon a second polarizer with transmission axis theta2, where theta2 - theta 1 = 90 degrees (in other words the two axes are perpendicular to one another). What is the intensity I_2 of the light beam emerging from the second polarizer?



2. Malus's Law



3. Would the answer be 0.25I0, i.e. the intensity is cut in half each time, so the final intensity is 1/4 the initial intensity?
 
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  • #2
Actually, is it just 0?
 
  • #3
Can light go through the crossed polarizers?

Half the intensity is transmitted if the incident beam is unpolarized, but after the first polarizer, it is polarized.


ehild
 

1. What is Malus's Law and how does it relate to intensity of light through two polarizers?

Malus's Law is a formula that describes the relationship between the intensity of light passing through two polarizers at different angles. It states that the intensity of light passing through two polarizers is equal to the initial intensity of light multiplied by the cosine squared of the angle between the polarizers.

2. How do you calculate the intensity of light using Malus's Law?

To calculate the intensity of light passing through two polarizers using Malus's Law, you need to know the initial intensity of light and the angle between the polarizers. You then multiply the initial intensity by the cosine squared of the angle between the polarizers to get the final intensity.

3. What is the purpose of using two polarizers in an experiment involving the intensity of light?

Two polarizers are used in experiments to study the intensity of light because they can control the amount of light that passes through them. By adjusting the angle between the two polarizers, scientists can study the effects of different intensities of light on various materials.

4. How does the angle between two polarizers affect the intensity of light passing through them?

The angle between two polarizers directly affects the intensity of light passing through them. As the angle increases, the intensity of light decreases according to Malus's Law. When the angle between the polarizers is 90 degrees, no light can pass through, resulting in zero intensity.

5. Can Malus's Law be applied to other types of waves besides light?

Yes, Malus's Law can be applied to any type of wave that exhibits polarization, such as radio waves or sound waves. As long as the wave can be polarized, the intensity can be calculated using Malus's Law.

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