# Solving Polarization Formula Problem: Get Help Now

• sghaussi
In summary, the conversation discusses a problem involving three stacked polarizing filters with varying angles of polarizing axis. The incident intensity of unpolarized light is given as 76.5 W/cm^2 after passing through the stack. The question is posed on what the intensity would be after removing the second filter. The solution involves using Malus' Law to calculate the intensity for two cases and comparing them. The conversation also clarifies some confusion regarding the positioning of the first filter and the use of 76.5 W/cm^2 as the maximum intensity.
sghaussi
Hello! I'm having difficulty solving this problem, I was wondering if you can help me solve it.

Three polarizing filters are stacked, with the polarizing axis of the second and third filters at angles of 28.4 and 57.0, respectively, to that of the first. If unpolarized light is incident on the stack, the light has an intensity of 76.5 W/cm^2 after it passes through the stack.

If the incident intensity is kept constant, what is the intensity of the light after it has passed through the stack if the second polarizer is removed?

I know I need to use the formula: I = I_max cos^2 phi

Do I solve for I_max first given the intensity 76.5 W/cm^2 then change the angle to fit the second situation? And what do they mean by "light is incident" on the stack? Does that mean I am looking for I or I_max?

I've read the section on Polarization 5 times so far and I still don't understand this problem. I hope you can help me. Thank you. =)

Last edited by a moderator:
Here's one way to approach it. Call the intensity of the light after passing through the first filter $I_1$. Now use your formula (which is Malus' Law) to calculate the intensity of the light for two cases:
(a) after passing through filter 2, then through filter 3
(b) after passing directly through filter 3​
Compare (a) with (b), realizing that the intensity you calculate for (a) is given as 76.5 W/cm^2.

Does this mean that filter one is positioned at zero degrees? Also, am I supposed to be using 76.5 W/cm^2 as my I_max or is that just the intensity given after the light has passed through all three filters? Do I just use the given intensity for find I_max? Thanks for your quick response - it's greatly appreciated!

sghaussi said:
Does this mean that filter one is positioned at zero degrees?
Yes.
Also, am I supposed to be using 76.5 W/cm^2 as my I_max or is that just the intensity given after the light has passed through all three filters?
As the problem stated: "...the light has an intensity of 76.5 W/cm^2 after it passes through the stack"
Do I just use the given intensity for find I_max?
Do what I suggested and see what happens.

## 1. What is a polarization formula problem?

A polarization formula problem refers to a mathematical equation used to calculate the degree of polarization of light passing through a polarizing filter. It involves understanding the properties of polarized light and using mathematical formulas to determine its intensity and direction.

## 2. Why is solving polarization formula problems important?

Solving polarization formula problems is important because it helps us understand the behavior of polarized light, which is essential in many scientific fields such as optics, physics, and astronomy. It also allows us to make accurate predictions and calculations in various applications, including polarized sunglasses, LCD screens, and polarimeters.

## 3. What are some common methods for solving polarization formula problems?

There are several methods for solving polarization formula problems, including Malus' law, Brewster's law, and the Jones calculus. Malus' law states that the intensity of polarized light passing through a polarizer is proportional to the square of the cosine of the angle between the polarizer and the incident light. Brewster's law relates the angle of incidence and the refractive index of a material to the angle at which light is polarized. The Jones calculus uses matrices to calculate the intensity and direction of polarized light passing through multiple polarizers.

## 4. Can I solve polarization formula problems without advanced mathematical knowledge?

Yes, it is possible to solve polarization formula problems without advanced mathematical knowledge. Basic algebra, trigonometry, and vector operations are usually sufficient for most problems. However, a solid understanding of polarized light and the properties of polarizing filters is necessary.

## 5. Where can I get help with solving polarization formula problems?

You can get help with solving polarization formula problems from various sources, such as textbooks, online resources, and scientific forums. You can also seek assistance from a tutor or your professor if you are a student. Additionally, some scientific calculators have built-in functions for solving polarization formula problems.

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