What is polarization?
41564#0
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. In some types of transverse waves, the wave displacement is limited to a single direction, so these also do not exhibit polarization; for example, in surface waves in liquids (gravity waves), the wave displacement of the particles is always in a vertical plane.
Polarization (waves)
584318#10
Political scientists have shown politicians have an incentive to advance and support polarized positions. These argue that during the early 1990s, the Republican Party used polarizing tactics to become the majority party in the United States House of Representatives—which political scientists Thomas E. Mann and Norman Ornstein refer to as Newt Gingrich's "guerrilla war." What political scientists have found is that moderates are less likely to run than are candidates who are in line with party doctrine, otherwise known as "party fit."Other theories state politicians who cater to more extreme groups within their party tend to be more successful, helping them stay in office while simultaneously pulling their constituency toward a polar extreme. A study by Nicholson (2012) found voters are more polarized by contentious statements from leaders of the opposing party than from the leaders of their own party. As a result, political leaders may be more likely to take polarized stances.
Polarization (politics)
3248054#1
Light reflected from a non-metallic surface becomes polarized; this effect is maximum at Brewster's angle, about 56° from the vertical for common glass. A polarizer rotated to pass only light polarized in the direction perpendicular to the reflected light will absorb much of it. This absorption allows glare reflected from, for example, a body of water or a road to be reduced. Reflections from shiny surfaces (e.g. vegetation, sweaty skin, water surfaces, glass) are also reduced. This allows the natural color and detail of what is beneath to come through. Reflections from a window into a dark interior can be much reduced, allowing it to be seen through. (The same effects are available for vision by using polarizing sunglasses.)
Polarizing filter (photography)
584318#6
Popular polarization, or mass polarization, occurs when the electorate's attitudes towards political issues, policies, and people are starkly divided along partisan lines. Members of the electorate and general public typically become less moderate in cases of popular polarization. In the U.S., media accounts typically simplify popular polarization to a divide between red states and blue states or a "culture war" between values-voters and progressives. Political scientists, though, generally agree that such accounts are too simplistic and ignore the complex factors that can account for polarization. Many political scientists consider political polarization a top-down process, in which elite polarization leads to – or at least precedes – popular polarization. However, polarization among elites does not necessarily produce polarization within the electorate, and polarized electoral choices can often reflect elite polarization rather than voters' preferences.
Polarization (politics)
584318#7
Political scientists studying popular polarization typically rely on data from opinion polls and election surveys. They look for trends in respondents' opinions on a given issue, their voting history, and their political ideology (conservative, liberal, moderate, etc.), and they try to relate those trends to respondents' party identification and other potentially polarizing factors (like geographic location or income bracket). Political scientists typically limit their inquiry to issues and questions that have been constant over time, in order to compare the present day to what the political climate has historically been. Oft-cited public opinion polls in the U.S. include those run by the Pew Research Center and Gallup, Inc., while political scientists also rely on more academic surveys, like the General Social Survey and the election surveys and "feeling thermometer" polls conducted by National Election Studies.
Polarization (politics)
2722105#36
In trying to appreciate how the quarter-wave plate transforms the linearly polarized light, it is important to realize that the two components discussed are not entities in and of themselves but are merely mental constructs one uses to help appreciate what is happening. In the case of linearly and circularly polarized light, at each point in space, there is always a single electric field with a distinct vector direction, the quarter-wave plate merely has the effect of transforming this single electric field.
Circular polarizers can also be used to selectively absorb or pass right-handed or left-handed circularly polarized light. It is this feature which is utilized by the 3D glasses in stereoscopic cinemas such as RealD Cinema. A given polarizer which creates one of the two polarizations of light will pass that same polarization of light when that light is sent through it in the other direction. In contrast it will block light of the opposite polarization.
Polarizer
2722105#0
A polarizer or polariser is an optical filter that lets light waves of a specific polarization pass through while blocking light waves of other polarizations. It can filter a beam of light of undefined or mixed polarization into a beam of well-defined polarization, that is polarized light. The common types of polarizers are linear polarizers and circular polarizers. Polarizers are used in many optical techniques and instruments, and polarizing filters find applications in photography and LCD technology. Polarizers can also be made for other types of electromagnetic waves besides light, such as radio waves, microwaves, and X-rays.
Polarizer
584318#2
Political scientists typically distinguish between two types of political polarization: elite polarization and popular polarization. "Elite polarization" refers to the polarization of political elites, like party organizers and elected officials, while "popular polarization" (or mass polarization) refers to the polarization in the electorate and general public. In either context, opinions and policy positions are characterized by strict adherence to party lines. Elite polarization and popular polarization can occur at the same time or independent of each other. A central issue in the study of political polarization is investigating the relationship between elite polarization and popular polarization, particularly any causal relationships between the two.
Polarization (politics)
41564#2
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 (such as glass) are isotropic and do not affect the polarization of light passing through them; however, some materials—those that exhibit birefringence, dichroism, or optical activity—can change the polarization of light. Some of these are used to make polarizing filters. Light is also partially polarized when it reflects from a surface.
Polarization (waves)
41564#76
Many animals are capable of perceiving some of the components of the polarization of light, e.g., linear horizontally polarized light. This is generally used for navigational purposes, since the linear polarization of sky light is always perpendicular to the direction of the sun. This ability is very common among the insects, including bees, which use this information to orient their communicative dances. Polarization sensitivity has also been observed in species of octopus, squid, cuttlefish, and mantis shrimp. In the latter case, one species measures all six orthogonal components of polarization, and is believed to have optimal polarization vision. The rapidly changing, vividly colored skin patterns of cuttlefish, used for communication, also incorporate polarization patterns, and mantis shrimp are known to have polarization selective reflective tissue. Sky polarization was thought to be perceived by pigeons, which was assumed to be one of their aids in homing, but research indicates this is a popular myth.
Polarization (waves)
41564#31
Unpolarized light can be described as a mixture of two independent oppositely polarized streams, each with half the intensity. Light is said to be "partially polarized" when there is more power in one of these streams than the other. At any particular wavelength, partially polarized light can be statistically described as the superposition of a completely unpolarized component and a completely polarized one. One may then describe the light in terms of the degree of polarization and the parameters of the polarized component. That polarized component can be described in terms of a Jones vector or polarization ellipse, as is detailed above. However, in order to also describe the degree of polarization, one normally employs Stokes parameters (see below) to specify a state of partial polarization.
Polarization (waves)