# What is Polarized light: Definition and 73 Discussions

Polarization (also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. A simple example of a polarized transverse wave is vibrations traveling along a taut string (see image); for example, in a musical instrument like a guitar string. Depending on how the string is plucked, the vibrations can be in a vertical direction, horizontal direction, or at any angle perpendicular to the string. In contrast, in longitudinal waves, such as sound waves in a liquid or gas, the displacement of the particles in the oscillation is always in the direction of propagation, so these waves do not exhibit polarization. Transverse waves that exhibit polarization include electromagnetic waves such as light and radio waves, gravitational waves, and transverse sound waves (shear waves) in solids.
An electromagnetic wave such as light consists of a coupled oscillating electric field and magnetic field which are always perpendicular to each other; by convention, the "polarization" of electromagnetic waves refers to the direction of the electric field. In linear polarization, the fields oscillate in a single direction. In circular or elliptical polarization, the fields rotate at a constant rate in a plane as the wave travels. The rotation can have two possible directions; if the fields rotate in a right hand sense with respect to the direction of wave travel, it is called right circular polarization, while if the fields rotate in a left hand sense, it is called left circular polarization.
Light or other electromagnetic radiation from many sources, such as the sun, flames, and incandescent lamps, consists of short wave trains with an equal mixture of polarizations; this is called unpolarized light. Polarized light can be produced by passing unpolarized light through a polarizer, which allows waves of only one polarization to pass through. The most common optical materials do not affect the polarization of light, however, some materials—those that exhibit birefringence, dichroism, or optical activity—affect light differently depending on its polarization. Some of these are used to make polarizing filters. Light is also partially polarized when it reflects from a surface.
According to quantum mechanics, electromagnetic waves can also be viewed as streams of particles called photons. When viewed in this way, the polarization of an electromagnetic wave is determined by a quantum mechanical property of photons called their spin. A photon has one of two possible spins: it can either spin in a right hand sense or a left hand sense about its direction of travel. Circularly polarized electromagnetic waves are composed of photons with only one type of spin, either right- or left-hand. Linearly polarized waves consist of photons that are in a superposition of right and left circularly polarized states, with equal amplitude and phases synchronized to give oscillation in a plane.Polarization is an important parameter in areas of science dealing with transverse waves, such as optics, seismology, radio, and microwaves. Especially impacted are technologies such as lasers, wireless and optical fiber telecommunications, and radar.

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1. ### I How different is a calcite crystal from a polarizer?

First of all, I apologize if I use incorrect terminology or I express myself poorly, I am trying my best. That said, I hope you guys are smart enough to understand me despite my shortcomings I know that calcite has birefringence, and I know that if you take calcite crystals and cut them and...
2. ### I Is Calcite a parallel to the Stern-Gerlach experiment?

When light passes through Calcite it is split into two beams opposite polarizations, doubling the image, and this sounds very similar to the Stern-Gerlach experiment where atoms are split into two beams with opposite polarizations The difference is that with light the opposite polarizations are...
3. ### Effect of a polarizer/analyzer on partially polarized light

This is problem 62 in Cutnell & Johnson's Physics (9th edition): Suppose that the light falling on the polarizer in the figure is partially polarized (average intensity \bar S_P) and partially upolarized (average intensity \bar S_U). The total incident intensity is \bar S_P+ \bar S_U and the...
4. ### I What happens when circular polarization meets a diagonal polarizer?

I'm finding what seems to be conflicting information on this question and could really use some help. It's my understanding that circularly polarized light is composed of two perpendicular linearly polarized components with a 90 degree phase shift between them. When considered individually...
5. ### Orientation of Major Axis for polarized light

Case 1 worked out great, I found it to be linearly polarized light at an angle ##\alpha = \frac{\pi}{4}##, but Case 2 is giving me trouble. As best I can tell, ##\alpha## is undefined in case 2. How do I solve case 2?
6. ### Please Explain My Polarized Light Experiments

I wanted to filter out reflections from glass. So I bought a camera with a "circular polarizing filter." It filters out polarized light, adjustable for orientation. The result confuses some cameras, so it also has a second stage which induces circular polarization. The results were...
7. ### Polarization of light -- Determine the thickness of the crystal

I don't even know where to start with this problem. What kind of slit makes linearly polarized light circularly polarized? The correct answer is d = lambda/(4(n1 - n2)) = 856nm. But how do I get there? Thanks in beforehand!
8. ### Elliptically polarized light & partially-polarized light

How to distinguish elliptical polarized light from partially-polarized light?
9. ### Polarized Light -- Idea for headlight safety

I've been a semi-pro photographer for a long, long time. I know the value of having a polarizing filter in my camera bag. I also wear polarized sunglasses for driving during the day. You can't beat 'em. I know some people who are complaining about these LED head lights from oncoming cars...
10. ### Elliptically polarized light incident at Brewster's angle

Elliptically polarized light strikes a glass surface (in air) with refraction index n at Brewster's angle. What is the polarization of the reflected ray? How does it change if now the glass surface is partially submerged in water? And if the glass surface is fully submerged in water? How...
11. ### 2 Polarizers attenuating a light beam

Homework Statement An angle is given between 2 polarizer's (45 degrees), through them light passes (unpolarized than after passing through the first one it polarizes), some of the light its shown on the display. For how much does the angle needs to be increased for the intensity of light to be...
12. ### Unpolarzied to polarized light

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...
13. ### Intensity of p-polarized light through stack of plates

As one know, the intensity Fresnel equations for the reflected p-polarized light $$\label{a} \frac{I_{p_{refl}}}{I_{0p}}=\frac {\tan^{2}(i-r)}{{\tan^{2}(i+r)}}$$ and for the refracted one is \label{b} \frac{I_{p_{refr}}}{I_{0p}}=1 - \frac...
14. ### How could 2 crossed fields polarize and deflect EM radiation

In the 1953 science fiction novel Childhood’s End by Arthur C. Clarke, characters use two crossed fields in outer space to block some of the solar radiation traveling towards earth: “Somehow, out in space, the light of the Sun had been polarized by two crossed fields so that no radiation could...
15. ### A Are green lasers Left Circularly Polarized Light?

I'm getting ready to do some testing, and need to decide which lasers to use . I need both left and right circularly polarized laser light . I was told that green diode lasers, the kind readily commercially available (usually around 200 - 500 mW.) , are LEFT CPL. 1. Is that usually true, and...
16. ### Circularly polarized light through a polarimeter

What happens when circularly polarized light goes through a polarimeter? In my experiment the polarimeter is made up of two crossed PEMs and a polarizer.
17. ### How is Circularly polarized light changed upon refraction?

I have a pretty good understanding that when polarized light is incident on a surface it will change handedness (Right handed polarization, to left handed polarization for example) and remains will remain circular if it is incident at an angle less than the Brewster angle, otherwise it will...
18. ### Can polarized light be recovered after passing through multiple mediums?

I was curious; having gone through a class covering Waves, in various forms encountered, we covered evanescent waves. These waves seen to be able to penetrate through some mediums, even able to be recovered. An example might be sound passing through water, then air, and then back into water...
19. ### How Is Polarized Light Propagation Determined from Electric and Magnetic Fields?

I am having problems completing the following questions: a) The answer is apparently in the -y direction (I understand that the direction of propagation is the cross product of the electric and magnetic field that must be perpendicular to each other). I am not sure how to come to this...
20. ### Does any kind of polarized light transfer heat?

Does any kind of polarized light transfer heat or any other form of energy? If possible give me some theory and related equation.
21. ### Transmission of polarized light

Today in lecture I learned that when light is polarized up and down (perpendicular to the plane of the incident beam) it is always reflected by some amount upon changing its medium of propagation, but when it is polarized side to side (parallel to the plane of the incident beam), there is an...
22. ### 2 layers of birefringent crystal, how many rays?

I am trying to solve a problem my camera exhibits. It has a sensor with 6000x3376 pixels. HD video is 1920x1080. In order to reduce the amount of information to the processor the camera throws away 2 out of 3 pixel lines. this creates a problem with thin lines tike telephone lines and makes...
23. ### Why is the birefringence pattern in a car colorless?

When looking through polarizing glasses at the rear window of a car (tempered glass), a black and white pattern appears. Supposedly, this is the same kind of birefringence that causes colored fringes in a plastic sheet, seen through a polarizer. It is clear that retardation and interference in...
24. ### Polarized light from any suface?

From a textbook I read something like this: "When sunlight is reflected from a horizontal surface, the plane of incidence is vertical, and the reflected light contains a preponderance of light that is polarized in the horizontal direction... The manufacturer makes the polarizing axis of the lens...
25. ### Could a Titan probe detect life with polarized light?

I had a thought and was wondering if it's viable to detecting whether or not life exists in Titan's hydrocarbon seas, whether we get direct evidence or not. Titan lakes are hydrocarbons, which likes to create twisted polymer chains. Nature (lightning, cosmic rays...) should produce polymers...
26. ### Why do enantiomers rotate polarized light?

We are currently learning about enantiomers in organic chemistry class. So far, we've covered what makes an enantiomer, the concept of chirality, optical isomer naming systems, and the physical and chemical properties of enantiomers. One of the physical properties listed is that enantiomers...
27. ### Major and minor axes of elliptically polarized light

Homework Statement Consider an elliptically polarized beam of light propagating along the z axis for which the E field components at a fixed position z are: Ex = E0cos(ωt) and Ey = E0cos(ωt +φ) Find the major and minor axes of the ellipse in terms of E0 and φ and sketch the ellipse in the...
28. ### Intensity of polarized light that has passed through two polarizing sheets

Homework Statement A beam of polarized light of intensity 43.0 W/m2 is sent through a system of two polarizing sheets. Relative to the polarization direction of that incident light, the polarizing directions of the sheets are at angles θ for the first sheet and 90 degrees for the second...
29. ### Vertically polarized light from a hene laser passes through a linear

Homework Statement 1. Vertically polarized light from a helium neon laser passes through a linear polarizer with its axis of polarization oriented 15° from the vertical axis. Assuming no absorption or reflection: (a) What percentage of the light will be transmitted? (b) What will be the...
30. ### Polarized light: Where did the magnetic field go?

Many of the diagrams of polarized light seem to show light with an electric field and a magnetic field approaching the polarizing filter, but only an electric field coming out of the filter. Where did the magnetic field* go? Does a filter that produces plane polarized light somehow eliminate...
31. ### Calculate Jones Vector of polarized light thorugh QWP

Homework Statement Find the final polarization in terms of Jones vectors for vertical polarized, coherent light passing through a quarter waveplate rotated \theta = \pi/4. The Jones matrix for the rotated waveplate is given as, J_Q = \frac{1}{\sqrt{2}} \cdot \left( \begin{array}{cc} 1...
32. ### Will two orthogonally polarized light beams interfere?

If Beam A (BA) is polarized vertically, and Beam B (BB) is polarized horizontally, can BA and BB still create an interference pattern if put together. For example, in Youngs Double Slit experiment, say BA goes through Slit 1, and BB goes through Slit 2: will an interference pattern result...
33. ### Polarized light and refraction

polarized light and refraction! Hi guys I need to discuss the polarized light in the waveguide and its refraction at an interface between two different media. if the light is polarized like in the picture(see attached) and oscillating only up and down (linear polarization), then does the...
34. ### Polarized light; maximum number of disagreements?

Polarized light and their disagreements Starting with 2 vertical photons, how can we argue that the maximum number of disagreements and minimum number for +30° and -30° is Nmin(-30°,30°) ≤ N(60°,0°) ≤ Nmax(-30°,30°)? and should we also not rotate the light?
35. ### Linearly polarized light on a quarter wave plate

Homework Statement A linearly polarized beam propagates in the z-direction with its E-field oscillating in the y-direction. It is incident on a quarter wave plate (QWP) located in the x-y plane at the origin. a. How should the fast and slow axes of the QWP be oriented if the beam emerging from...
36. ### Coherency matrix of partially polarized light incomplete?

The electric field of quasi-monochromatic, partially polarized light can be expressed by the following random process (Goodman, Statistical optics) \bar{E}(t,\bar{x})=u_{x}(t,\bar{x})\bar{e}_{x}+u_{y}(t,\bar{y})\bar{e}_{y} u_{x}(t,\bar{x})=\Psi_{x} e^{i(\bar{k}\cdot\bar{x}-\omega t)}...
37. ### Polarized Light and Quantum Spin

Can there be EM radiation with spin zero? I don't mean that the sum of all spins is zero, as it usually is. My thinking is that all light spins and usually the left and right component is of equal intensity. Am I correct in thinking that light reflecting off of a suitable horizontal...
38. ### Intensity of elliptically polarized light

The time averaged norm of the Poynting vector of this electromagnetic field (elliptically polarized light): \begin{split} \bar{E}(t,\bar{x})=&(\bar{E}_{0x}+\bar{E}_{0y}e^{i \delta})e^{\bar{k}\cdot\bar{x}-\omega t}\\ \bar{B}(t,\bar{x})=&\frac{1}{\omega}(\bar{k}\times\bar{E}(t,\bar{x}))...
39. ### Hydrogen excited with polarized light?

Hello, First of all, i know I should use the template for this, and I apologize for that, but the thing is I don't even know how to begin to solve the next problem, and it's very important for me and for my tomorrow's afternoon exam. It's quite qualitative, and I'm sure most of you will know...
40. ### Linear polarized light and polarisation

hi if you have linear polarized light and you have a metal grid and the angle between the e-vector and the metal grid is 30°. now you split up the e-vector in one component parallel and one component perpendicular to the metal grid. okay. so the component of the wave, that survives this...
41. ### Passing elliptically polarized light through a linear polarizer

Hi Here (https://www.physicsforums.com/showthread.php?t=119847) it is mentioned that the intensity when passing elliptically polarized light through a linear polarizer will vary when turning the polarizer. Doesn't this only hold assuming the two components of the light are not equal? I mean...
42. ### Why is it only chiral molecules that rotate plane polarized light?

I just read that the reason molecules rotate plane polarized light is because the light interacts with the electron cloud of the molecule. That makes sense but why aren't achiral molecules optically active? Achiral molecules have electron clouds too so why don't their electron clouds cause...
43. ### Is Natural Unpolarized Light Equivalent to Randomly Fluctuating Elliptic Light?

Hi We can represent natural unpolarized light as a sum of two orthogonal, linearly polarized components with a randomly fluctuating phase difference. Is it correct to say that this is equivalent to representing it as elliptic light, where the ellipticity fluctuates randomly in time? Niles.
44. ### Jones vector of circularly polarized light

Why is the jones vector of circularly polarized light <1,i> ? Things like <1,0> and <0,1> make perfect sense for linearly polarized light along the x and y axes but what exactly is that i doing there that makes the vector represent a circular polarization? I never really intuitively...
45. ### Can circularly polarized light interfere with linearly polarized

Can circularly polarized light interfere with linearly polarized light?
46. ### Circularly polarized light rotation rate

I have a question about circularly polarized light. Is the rate at which the electric field vector rotates proportional to the light’s frequency, or is the rate of rotation unrelated to the light’s frequency? What got me wondering about this was thinking about relativity: Since all observers...
47. ### Polarized Light and Filters: Understanding the Basics

Homework Statement Not really a problem, but a question that my professor could not answer (Well the TA). Homework Equations The Attempt at a Solution In an image such as this, illustrating polarized light: I have 2 questions. 1.) Are the filters illustrated with slats as an...
48. ### How Can Optical Devices Like QWP and HWP Determine the Polarization of Light?

Hi, how we can determine the right or left circularly polarized light by using the optical devices such QWP or HWP or others.
49. ### Difference between coherent light and polarized light

What is the difference between coherent light and polarized light?
50. ### Why does polarized light shift color in reflections on the sea?

Hello. I've noticed a thing i could not understand, and hope someone can explain it to me. Given: The sun at about 45* angle above, the calm sea flat below. The sky is gray with thin, fog-like clouds. There is a reflection in the sea of the sun above...