Need help with question regarding polarization filters

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Un-polarized light passing through two polarization filters with misaligned transmission axes results in 18% of the light being transmitted. The initial intensity of the light is halved after passing through the first ideal filter, leading to linearly polarized light. The calculation for the angle between the filters involves using the formula I = Imax(cosΦ)^2, but the correct angle is 53 degrees, not 64 degrees. The discussion emphasizes understanding how the first filter affects the intensity and polarization of the light. Clarifications and support were provided throughout the conversation, highlighting the collaborative nature of the forum.
ZHIHUI
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Moved from a technical forum, so homework template missing
Un-polarized light is incident upon two polarization filters and do not have their transmission axes aligned. If 18% of the light passes through this combination of filters, what is the angle between the transmission axes of the filters.

I got 64 degrees using I = Imax(cosΦ)^2 but the correct answer is 53 degrees.

Thank you very much!
 
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What happens when the light hits the first filter?
 
DrClaude said:
What happens when the light hits the first filter?
The light will be linearly polarized. If the first filter is ideal, intensity of the transmitted light will be exactly half that of the incident un-polarized light.
 
ZHIHUI said:
The light will be linearly polarized. If the first filter is ideal, intensity of the transmitted light will be exactly half that of the incident un-polarized light.
Correct. So how does that affect the terms in your equation?
 
DrClaude said:
Correct. So how does that affect the terms in your equation?
I got it!
Thank you very much!
Sorry for the trouble!
 
ZHIHUI said:
I got it!
Thank you very much!
Sorry for the trouble!
No trouble, that what PF is for!
 

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