What is "polarization"

Polarization \Po`lar*i*za"tion\, n. [Cf. F. polarisation.]

1. The act of polarizing; the state of being polarized, or of having polarity.

2. (Opt.) A peculiar affection or condition of the rays of light or heat, in consequence of which they exhibit different properties in different directions.

   Note: If a beam of light, which has been reflected from a plate of unsilvered glass at an angle of about 56[deg], be received upon a second plate of glass similar to the former, and at the same angle of incidence, the light will be readily reflected when the two planes of incidence are parallel to each other, but will not be reflected when the two planes of incidence are perpendicular to each other. The light has, therefore, acquired new properties by reflection from the first plate of glass, and is called polarized light, while the modification which the light has experienced by this reflection is called polarization. The plane in which the beam of light is reflected from the first mirror is called the plane of polarization. The angle of polarization is the angle at which a beam of light must be reflected, in order that the polarization may be the most complete. The term polarization was derived from the theory of emission, and it was conceived that each luminous molecule has two poles analogous to the poles of a magnet; but this view is not now held. According to the undulatory theory, ordinary light is produced by vibrations transverse or perpendicular to the direction of the ray, and distributed as to show no distinction as to any particular direction. But when, by any means, these, vibrations are made to take place in one plane, the light is said to be plane polarized. If only a portion of the vibrations lie in one plane the ray is said to be partially polarized. Light may be polarized by several methods other than by reflection, as by refraction through most crystalline media, or by being transmitted obliquely through several plates of glass with parallel faces. If a beam of polarized light be transmitted through a crystal of quartz in the direction of its axis, the plane of polarization will be changed by an angle proportional to the thickness of the crystal. This phenomenon is called rotatory polarization. A beam of light reflected from a metallic surface, or from glass surfaces under certain peculiar conditions, acquires properties still more complex, its vibrations being no longer rectilinear, but circular, or elliptical. This phenomenon is called circular or elliptical polarization.

3. (Elec.) An effect produced upon the plates of a voltaic battery, or the electrodes in an electrolytic cell, by the deposition upon them of the gases liberated by the action of the current. It is chiefly due to the hydrogen, and results in an increase of the resistance, and the setting up of an opposing electro-motive force, both of which tend materially to weaken the current of the battery, or that passing through the cell.

1812, from polarize + -ation, and in part from French polarisation, noun of action from polariser. Figuratively from 1871; of social and political groups, "accentuation of differences," from 1945.

n. 1 the production, or the condition of polarity 2 (context physics English) the production of polarized light; the direction in which the electric field of an electromagnetic wave points 3 (context chemistry physics English) the separation of positive and negative charges in a nucleus, atom, molecule or system 4 the grouping of opinions into two extremes

1. n. the phenomenon in which waves of light or other radiation are restricted in direction of vibration [syn: polarisation]

2. the condition of having or giving polarity [syn: polarisation]

In the world of politics, polarization (or polarisation) can refer to the divergence of political attitudes to ideological extremes. Polarization can refer to such divergence like public opinion or even to such divergence within certain groups. Almost all discussions of polarization in political science consider polarization in the context of political parties and democratic systems of government. When polarization occurs in a two-party system, like the United States, moderate voices often lose power and influence. According to the Pew Forum, America has never been more polarized, except perhaps during the period leading up to the American Civil War.

Polarization or polarisation can refer to:

Polarization is an album by American jazz trombonist and composer Julian Priester recorded in 1977 and released on the ECM label.

Polarization ( also polarisation) is a parameter applying to waves that specifies the geometrical orientation of the oscillation. Electromagnetic waves such as light exhibit multiple polarizations, as do many other types of waves such as gravitational waves and sound waves in solids. On the other hand, sound waves in a gas or liquid only oscillate in the wave's direction of propagation, and the oscillation of ocean waves is always in the vertical direction. In these cases one doesn't normally speak of "polarization" since the oscillation's direction is not in question.

In an electromagnetic wave, both the electric field and magnetic field are oscillating but in different directions; by convention the "polarization" of light refers to the polarization of the electric field. Light which can be approximated as a plane wave in free space or in an isotropic medium propagates as a transverse wave—both the electric and magnetic fields are perpendicular to the wave's direction of travel. The oscillation of these fields may be in a single direction ( linear polarization), or the field may rotate at the optical frequency ( circular or elliptical polarization). In that case the direction of the fields' rotation, and thus the specified polarization, may be either clockwise or counter clockwise; this is referred to as the wave's chirality or handedness.

The most common optical materials (such as glass) are isotropic and simply preserve the polarization of a wave but do not differentiate between polarization states. However, there are important classes of lossless materials classified as birefringent or optically active in which this is not the case and a wave's polarization will generally be modified or will affect propagation through it. In linear dichroism and circular dichroism, attenuation in propagation is dependent on the wave's polarization. One familiar example is the polarizer, an optical filter that transmits only one polarization.

Polarization is an important parameter in areas of science dealing with transverse wave propagation, such as optics, seismology, radio, and microwaves. Especially impacted are technologies such as lasers, wireless and optical fiber telecommunications, and radar.

According to quantum mechanics, the energy, linear momentum, and angular momentum of an electromagnetic wave are quantized in the form of photons. Then there is an identification between the electromagnetic polarization of the wave and polarization operators which determine the probability of a photon to be found in a given polarization state. In particular, the spin operator is shown to correspond to the basis states of circular polarization as described below in terms of electromagnetic fields. This is described in detail at Photon polarization.

Polarization in communications and psychology, is the definition given to the behavior of a social or political group to split based on opposing views. Over time, more and more members of the original group join one or the other split group and fewer and fewer members remain neutral. This brings the two sides or "poles" further and further apart.

During polarization, there is a tendency for the opposing sides of the argument to make increasingly disagreeable statements, thereby creating more and more distance between the two sides. This is known as the "pendulum effect". Thus, it is commonly observed in polarized groups that judgments made after group discussion on a given subject tend to be more extreme than judgments made by individual group members prior to the discussion.

This process is also known as 'group polarization'. In the past, it was referred to as the 'risky shift phenomenon' and particularly referenced decision-making by a jury.

Studies have surprisingly found that groups make riskier decision than individuals do. An example of this is given in a study conducted by Wallach and colleagues: When deciding alone, people said the chess player should make risky choices only if the chances of success are 30% or higher. However, after discussing the issue with other participants in the a group, people changed their mind and decided that the chess player should go for the move even if there was only a 10% chance of success.

Polarization is also a term used in biological psychology to describe the process of a neural membrane accumulating ions of opposing polarity.

In electrochemistry, polarization is a collective term for certain mechanical side-effects (of an electrochemical process) by which isolating barriers develop at the interface between electrode and electrolyte. These side-effects influence the reaction mechanisms, as well as the chemical kinetics of corrosion and metal deposition.

The term 'polarization' derives from the early 19th-century discovery that electrolysis causes the elements in an electrolyte to be attracted towards one or the other pole i.e. the gasses were polarized towards the electrodes. Thus, initially 'polarization' was essentially a description of electrolysis itself, and in the context of electrochemical cells used to describe the effects on the electrolyte (which was then called "polarization liquid"). In time, as more electrochemical processes were invented, the term 'polarization' evolved to denote any (potentially undesirable) mechanical side-effects that occur at the interface between electrolyte and electrodes.

These mechanical side-effects are:

• activation polarization: the accumulation of gasses (or other non- reagent products) at the interface between electrode and electrolyte.
• concentration polarization: uneven depletion of reagents in the electrolyte cause concentration gradients in boundary layers.

Both effects isolate the electrode from the electrolyte, impeding reaction and charge transfer between the two. The immediate consequences of these barriers are:

• the reduction potential decreases, the reaction rate slows and eventually halts.
• electric current is increasingly converted into heat rather than into desired electrochemical work.
• as predicted by Ohm's law, either electromotive force decreases and current increases, or vice-versa.
• the self-discharge rate increases in electrochemical cells.

Each of these immediate consequences has multiple secondary effects. For instance, heat affects the crystalline structure of the electrode material. This in turn can influence reaction rate, and/or accelerate dendrite formation, and/or deform the plates, and/or precipitate thermal runaway.

The mechanical side-effects can be desirable in some electrochemical processes, for example, certain types of electropolishing and electroplating take advantage of the fact that evolved gasses will first accumulate in the depressions of the plate. This feature can be used to reduce current in the depressions, and exposes ridges and edges to higher currents. Undesirable polarization can be suppressed by vigorous agitation of the electrolyte, or when agitation is impractical (such as in a stationary battery) with a depolarizer.

Economists refers to the polarization of the labor force when middle-class jobs—requiring a moderate level of skills, like autoworkers’ jobs—appear to disappear relative to those at the bottom, requiring few skills, and those at the top, requiring greater skill levels. The structure of job opportunities in the United States has sharply polarized over the past two decades, with expanding job opportunities in both high-skill, high-wage occupations and low-skill, low wage occupations, coupled with contracting opportunities in middle-wage, middle-skill white-collar and blue-collar jobs. Although this has contributed to the rise of income inequality in the U.S. it is a minor factor compared to the relatively rapid rise in income and wealth by the top 1%. Although income and wealth inequality are uniquely American phenomena of the past decades in industrialized countries, employment and economic polarization is widespread across industrialized economies; it is not a uniquely American phenomenon. Over the past decades, wage gains were also polarized, with modest gains at the extremes and smaller gains in the middle. A good description of polarization in Great Britain is one of the first uses the term, economic polarization.