Effect of rotating polarizer on intensity of transmitted light

In summary, the conversation discusses the law of polarizers, specifically the Law of Malus, which states that the transmitted intensity of light through a polarizer is equal to the incident intensity multiplied by the square of the cosine of the angle between the direction of the polarizer and the polarized light. The problem at hand involves a polarized light with an incident intensity of 8W[m][/-2] and a transmitted intensity of 2W[m][/-2], and asks for the new transmitted intensity when the polarizer is rotated 90 degrees. The solution involves using the Law of Malus to calculate the new transmitted intensity, which is found to be 6W[m][/-2] by taking the square root of the difference
  • #1
NihalRi
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Homework Statement



Plane polarised is incident normally on a polerizer which can rotate in plane perpendicular to light. The intensity of of incident light is 8W[m][/-2] and transmitted intensity is 2W[m][/-2] if polerizer is rotated 90 deg what is the new transmitted intensity

Homework Equations

The Attempt at a Solution


Root of (8 squared minus 2 squared)=root 60
Resolving vectors?
Answer was 6W[m][/-2]
Which is just eight minus two, help? I don't know why
 
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  • #2
What is the law for polarizers? In other words, what relevant equation applies to polarizers?
 
  • #3
gneill said:
What is the law for polarizers? In other words, what relevant equation applies to polarizers?
Transmitted intensity = incident intensity times cosine there
Where theta is the angle between the direction of the polerizer and the polarised light
 
  • #4
NihalRi said:
Transmitted intensity = incident intensity times cosine there
Where theta is the angle between the direction of the polerizer and the polarised light
Close, but not quite: the cosine should be squared. Look up "Law of Malus" (or Malus's Law).
 
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Related to Effect of rotating polarizer on intensity of transmitted light

1. How does a rotating polarizer affect the intensity of transmitted light?

The intensity of transmitted light is directly proportional to the angle of rotation of the polarizer. When the polarizer is rotated, it blocks certain orientations of light, resulting in a decrease in intensity.

2. Does the intensity of transmitted light change with the angle of rotation?

Yes, the intensity of transmitted light changes as the polarizer is rotated. The intensity is highest when the polarizer is aligned with the polarization direction of the incident light and decreases as the angle of rotation increases.

3. What happens to the intensity of transmitted light when the polarizer is rotated to 90 degrees?

When the polarizer is rotated to 90 degrees, the intensity of transmitted light becomes zero. This is because the polarizer blocks all orientations of light, resulting in no light being transmitted.

4. How does the material of the polarizer affect the intensity of transmitted light?

The material of the polarizer affects the intensity of transmitted light by determining its ability to block certain orientations of light. Different materials have different polarizing properties, which can result in varying levels of intensity of transmitted light.

5. Is there a limit to how much the intensity of transmitted light can change with a rotating polarizer?

Yes, there is a limit to how much the intensity of transmitted light can change with a rotating polarizer. This limit is reached when the polarizer is rotated to 90 degrees, as no light can be transmitted at this angle.

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