![]() ![]() The magnetic field B (or H) is always at right angles to it (blue), and both are perpendicular to the direction of propagation ( z).Įlectromagnetic waves (such as light), traveling in free space or another homogeneous isotropic non-attenuating medium, are properly described as transverse waves, meaning that a plane wave's electric field vector E and magnetic field H are each in some direction perpendicular to (or "transverse" to) the direction of wave propagation E and H are also perpendicular to each other. Transverse electromagnetic waves A "vertically polarized" electromagnetic wave of wavelength λ has its electric field vector E (red) oscillating in the vertical direction. Incoherent states can be modeled stochastically as a weighted combination of such uncorrelated waves with some distribution of frequencies (its spectrum), phases, and polarizations. Characterizing an optical system in relation to a plane wave with those given parameters can then be used to predict its response to a more general case, since a wave with any specified spatial structure can be decomposed into a combination of plane waves (its so-called angular spectrum). ![]() However, for understanding electromagnetic waves and polarization in particular, it is easier to just consider coherent plane waves these are sinusoidal waves of one particular direction (or wavevector), frequency, phase, and polarization state. Most sources of light are classified as incoherent and unpolarized (or only "partially polarized") because they consist of a random mixture of waves having different spatial characteristics, frequencies (wavelengths), phases, and polarization states. Wave propagation and polarization cross linear polarized Especially impacted are technologies such as lasers, wireless and optical fiber telecommunications, and radar. Polarization is an important parameter in areas of science dealing with transverse waves, such as optics, seismology, radio, and microwaves. 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. Circularly polarized electromagnetic waves are composed of photons with only one type of spin, either right- or left-hand. 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. When viewed in this way, the polarization of an electromagnetic wave is determined by a quantum mechanical property of photons called their spin. Light also becomes partially polarized when it reflects at an angle from a surface.Īccording to quantum mechanics, electromagnetic waves can also be viewed as streams of particles called photons. Some of these are used to make polarizing filters. 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. Polarized light can be produced by passing unpolarized light through a polarizer, which allows waves of only one polarization to pass through. 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. In circular or elliptical polarization, the fields rotate at a constant rate in a plane as the wave travels, either in the right-hand or in the left-hand direction. ![]() In linear polarization, the fields oscillate in a single direction. Transverse waves that exhibit polarization include electromagnetic waves such as light and radio waves, gravitational waves, and transverse sound waves ( shear waves) in solids.Īn 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 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. 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. 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. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. ![]() Polarization ( also polarisation) is a property of transverse waves which specifies the geometrical orientation of the oscillations. Circular polarization on rubber thread, converted to linear polarization ![]()
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