Editing Polarization (waves) (section)

{{short description|Property of waves that can oscillate with more than one orientation}}
{{Other uses|Polarization (disambiguation){{!}}Polarization}}
{{Use American English|date= July 2023}}
[[File:Polarizacio.jpg|thumb|upright=1.25|Circular polarization on rubber thread, converted to linear polarization]]
'''{{lang|en|Polarization|italics=no}}''' ([[American and British English spelling differences|also]] '''{{lang|en-GB|polarisation|italics=no}}''') is a property of [[transverse waves]] which specifies the geometrical orientation of the [[oscillation]]s.<ref name="Shipman">{{cite book
 | last1  = Shipman
 | first1 = James
 | last2  = Wilson
 | first2 = Jerry D.
 | last3  = Higgins
 | first3 = Charles A.
 | title  = An Introduction to Physical Science, 14th Ed.
 | publisher = Cengage Learning
 | date   = 2015
 | pages  = 187
 | url    = https://books.google.com/books?id=NoTCBAAAQBAJ&q=polarization+transverse+wave+longitudinal&pg=PA187
 | isbn   = 978-1-305-54467-3
 }}</ref><ref name="Muncaster">{{cite book
 | last1  = Muncaster
 | first1 = Roger
 | title  = A-level Physics
 | publisher = Nelson Thornes
 | date   = 1993
 | pages  = 465–467
 | url    = https://books.google.com/books?id=Knov8XAyf2cC&q=polarization+transverse+wave+longitudinal&pg=PA465
 | isbn   = 0-7487-1584-3
 }}</ref><ref name="Singh">{{cite book
 | last1  = Singh
 | first1 = Devraj
 | title  = Fundamentals of Optics, 2nd Ed.
 | publisher = PHI Learning Pvt. Ltd.
 | date   = 2015
 | pages  = 453
 | url    = https://books.google.com/books?id=cTB8CgAAQBAJ&q=polarization+transverse+wave+longitudinal&pg=PA453
 | isbn   = 978-8120351462
 }}</ref><ref name="Avadhanulu">{{cite book
 | last1  = Avadhanulu
 | first1 = M. N.
 | title  = A Textbook of Engineering Physics
 | publisher = S. Chand Publishing
 | date   = 1992
 | pages  = 198–199
 | url    = https://books.google.com/books?id=lTUNWOR_cDgC&q=polarization+transverse+wave+longitudinal&pg=PA198
 | isbn   = 8121908175
 }}</ref><ref name="Desmarais">{{cite book
 | last1  = Desmarais
 | first1 = Louis
 | title  = Applied Electro Optics
 | publisher = Pearson Education
 | date   = 1997
 | pages  = 162–163
 | url    = https://books.google.com/books?id=GbgG0v1BP2YC&q=polarization+transverse+wave+longitudinal&pg=PT162
 | isbn   = 0-13-244182-9
 }}</ref>  In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave.<ref name="Avadhanulu" />  One 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 wave]]s, such as [[sound wave]]s 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 wave]]s such as [[light]] and [[radio wave]]s, [[gravitational wave]]s,<ref>{{cite book
 | last1 = Le Tiec | first1 =  A.
 | title = An Overview of Gravitational Waves
 | pages = 1–41
 | last2 = Novak | first2 = J.
 | chapter =Theory of Gravitational Waves
 | arxiv=1607.04202
 | date = July 2016
 | doi=10.1142/9789813141766_0001
| isbn = 978-981-314-175-9
 | s2cid = 119283594
 }}</ref> and transverse sound waves ([[shear wave]]s) 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. Different states of polarization correspond to different relationships between polarization and the direction of propagation. In [[linear polarization]], the fields oscillate in a single direction.  In [[circular polarization|circular]] or [[elliptical polarization]], the fields rotate at a constant rate in a plane as the wave travels, either in the [[right hand rule|right-hand]] or in the left-hand direction.

Light or other electromagnetic radiation from many sources, such as the sun, flames, and [[incandescent lamp]]s, 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, but 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 also becomes partially polarized when it reflects at an angle from a surface.

According to [[quantum mechanics]], electromagnetic waves can also be viewed as [[stream of particles|streams of particles]] called [[photon]]s.  When viewed in this way, the polarization of an electromagnetic wave is determined by a quantum mechanical property of photons called their [[Spin (physics)|spin]].<ref name="Lipson">{{cite book
 | last1  = Lipson
 | first1 =  Stephen G.
 | last2  = Lipson
 | first2 = Henry
 | last3  = Tannhauser
 | first3 = David Stefan
 | title  = Optical Physics
 | publisher = Cambridge University Press
 | date   = 1995
 | pages  = 125–127
 | url    = https://books.google.com/books?id=wlylmCXMZicC&q=polarization+photon+spin&pg=PA126
 | isbn   = 978-0-521-43631-1
 }}</ref><ref name="Waldman">{{cite book
 | last1  = Waldman
 | first1 = Gary
 | title  = Introduction to Light: The Physics of Light, Vision, and Color
 | publisher = Courier Corporation
 | date   = 2002
 | pages  = 79–80
 | url    = https://books.google.com/books?id=PbsoAXWbnr4C&q=polarization+spin+light+photon&pg=PA80
 | isbn   =  978-0-486-42118-6
 }}</ref>  A photon has one of two possible spins: it can either spin in a [[right hand rule|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.<ref name="Waldman" />

Polarization is an important parameter in areas of science dealing with transverse waves, such as [[optics]], [[seismology]], [[radio]], and [[microwave]]s. Especially impacted are technologies such as [[laser]]s, wireless and optical fiber [[telecommunications]], and [[radar]].