Transverse wave

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Transverse plane wave in linear polarization, i.e. oscillating only in the y-direction.
The wave shown could occur on a water surface.
(Although strictly speaking water waves have a small longitudinal component as well.) Onde cisaillement impulsion 1d 30 petit.gif
Transverse plane wave in linear polarization, i.e. oscillating only in the y-direction.
The wave shown could occur on a water surface.
(Although strictly speaking water waves have a small longitudinal component as well.)
A light wave is an example of a transverse electromagnetic wave; the shape of the wave is one of the sinusoidal plane-wave solutions of the electromagnetic wave equation. Light-wave.svg
A light wave is an example of a transverse electromagnetic wave; the shape of the wave is one of the sinusoidal plane-wave solutions of the electromagnetic wave equation.
Propagation of a transverse spherical wave in a 2d grid (empirical model) Ondes cisaillement 2d 20 petit.gif
Propagation of a transverse spherical wave in a 2d grid (empirical model)

A transverse wave is a moving wave that consists of oscillations occurring perpendicular (right angled) to the direction of energy transfer (or the propagation of the wave).

Contents

If a transverse wave is moving in the positive x-direction, its oscillations are in up and down directions that lie in the y–z plane.

Light is an example of a transverse wave, while sound is a longitudinal wave. A ripple in a pond and a wave on a string are easily visualized as transverse waves.

Longitudinal wave waves in which the displacement of the medium is in the same direction as, or the opposite direction to, the direction of propagation of the wave

Longitudinal waves are waves in which the displacement of the medium is in the same direction as, or the opposite direction to, the direction of propagation of the wave. Mechanical longitudinal waves are also called compressional or compression waves, because they produce compression and rarefaction when traveling through a medium, and pressure waves, because they produce increases and decreases in pressure.

Explanation

Transverse waves are waves that are oscillating perpendicularly (at a right angle) to the direction of propagation. If you anchor one end of a ribbon or string and hold the other end in your hand, you can create transverse waves by moving your hand up and down. Notice though, that you can also launch waves by moving your hand side-to-side. This is an important point. There are two independent directions in which wave motion can occur. In this case, these motions are the Y and Z directions mentioned above, while the wave propagates away in the X direction. The other type of waves is the longitudinal wave, which oscillates in the direction of its propagation.

"Polarized" waves

Continuing with the string example, if you move your hand in a clockwise circle, you will launch waves in the form of a left-handed helix as they propagate away. Similarly, if you move your hand in a counter-clockwise circle, a right-handed helix will form. These phenomena of simultaneous motion in two directions go beyond the kinds of waves we observe on the surface of water - in that a wave on a string can be two-dimensional.

Two-dimensional transverse waves exhibit a phenomenon called polarization. A wave produced by moving your hand in a straight line, up and down for instance, is a linearly polarized wave, a special case. A wave produced by moving your hand in a circle or an ellipse is a circularly or elliptically polarized wave, two other special cases.

Polarization (waves) property of waves that can oscillate with more than one orientation

Polarization 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 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, the wave displacement of the particles is always in a vertical plane.

In electrodynamics, linear polarization or plane polarization of electromagnetic radiation is a confinement of the electric field vector or magnetic field vector to a given plane along the direction of propagation. See polarization and plane of polarization for more information.

Ellipse type of curve on a plane

In mathematics, an ellipse is a curve in a plane surrounding two focal points such that the sum of the distances to the two focal points is constant for every point on the curve. As such, it is a generalization of a circle, which is a special type of an ellipse having both focal points at the same location. The elongation of an ellipse is represented by its eccentricity, which for an ellipse can be any number from 0 to arbitrarily close to but less than 1.

Electromagnetic waves

Electromagnetic waves behave in this same way. Electromagnetic waves are also two-dimensional transverse waves. Transverse waves are waves that travel perpendicular to the direction of the vibration. Ray theory does not describe phenomena such as interference and diffraction, which require wave theory (involving the phase of the wave). You can think of a ray of light, in optics, as an idealized narrow beam of electromagnetic radiation. Rays are used to model the propagation of light through an optical system, by dividing the real light field up into discrete rays that can be computationally propagated through the system by the techniques of ray tracing. [1] A light ray is a line or curve that is perpendicular to the light's wavefronts (and is therefore collinear with the wave vector). Light rays bend at the interface between two dissimilar media and may be curved in a medium in which the refractive index changes. Geometric optics describes how rays propagate through an optical system. [1]

In optics a ray is an idealized model of light, obtained by choosing a line that is perpendicular to the wavefronts of the actual light, and that points in the direction of energy flow. Rays are used to model the propagation of light through an optical system, by dividing the real light field up into discrete rays that can be computationally propagated through the system by the techniques of ray tracing. This allows even very complex optical systems to be analyzed mathematically or simulated by computer. Ray tracing uses approximate solutions to Maxwell's equations that are valid as long as the light waves propagate through and around objects whose dimensions are much greater than the light's wavelength. Ray theory does not describe phenomena such as interference and diffraction, which require wave theory.

Optics The branch of physics that studies light

Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties.

Light electromagnetic radiation in or near visible spectrum

Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which is the visible spectrum that is visible to the human eye and is responsible for the sense of sight. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), or 4.00 × 10−7 to 7.00 × 10−7 m, between the infrared and the ultraviolet. This wavelength means a frequency range of roughly 430–750 terahertz (THz).

This two-dimensional nature should not be confused with the two components of an electromagnetic wave, the electric and magnetic field components, which are shown in the light wave diagram here. Each of these fields, the electric and the magnetic, exhibits two-dimensional transverse wave behavior, just like the waves on a string.

See also

Luminiferous aether postulated medium for the propagation of light

Luminiferous aether or ether, was the postulated medium for the propagation of light. It was invoked to explain the ability of the apparently wave-based light to propagate through empty space, something that waves should not be able to do. The assumption of a spatial plenum of luminiferous aether, rather than a spatial vacuum, provided the theoretical medium that was required by wave theories of light.

Shear wave splitting

Shear wave splitting, also called seismic birefringence, is the phenomenon that occurs when a polarized shear wave enters an anisotropic medium. The incident shear wave splits into two polarized shear waves. Shear wave splitting is typically used as a tool for testing the anisotropy of an area of interest. These measurements reflect the degree of anisotropy and lead to a better understanding of the area’s crack density and orientation or crystal alignment. We can think of the anisotropy of a particular area as a black box and the shear wave splitting measurements as a way of looking at what is in the box.

Sinusoidal plane-wave solutions are particular solutions to the electromagnetic wave equation.

Related Research Articles

Electromagnetic radiation form of energy emitted and absorbed by charged particles, which exhibits wave-like behavior as it travels through space

In physics, electromagnetic radiation refers to the waves of the electromagnetic field, propagating (radiating) through space, carrying electromagnetic radiant energy. It includes radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, and gamma rays.

Wave oscillation that travels through space and matter

In physics, a wave is a disturbance that transfers energy through matter or space, with little or no associated mass transport. Waves consist of oscillations or vibrations of a physical medium or a field, around relatively fixed locations. From the perspective of mathematics, waves, as functions of time and space, are a class of signals.

Brewsters angle

Brewster's angle is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection. When unpolarized light is incident at this angle, the light that is reflected from the surface is therefore perfectly polarized. This special angle of incidence is named after the Scottish physicist Sir David Brewster (1781–1868).

Circular polarization

In electrodynamics, circular polarization of an electromagnetic wave is a polarization state in which, at each point, the electric field of the wave has a constant magnitude but its direction rotates with time at a steady rate in a plane perpendicular to the direction of the wave.

Plane wave Type of wave propagating in 3 dimensions

In the physics of wave propagation, a plane wave is a wave whose wavefronts are infinite parallel planes. Mathematically a plane wave takes the form

Surface wave mechanical wave that propagates along the interface between differing media

In physics, a surface wave is a 90 degree wave that propagates along the interface between differing media. A common example is gravity waves along the surface of liquids, such as ocean waves. Gravity waves can also occur within liquids, at the interface between two fluids with different densities. Elastic surface waves can travel along the surface of solids, such as Rayleigh or Love waves. Electromagnetic waves can also propagate as "surface waves" in that they can be guided along a refractive index gradient or along an interface between two media having different dielectric constants. In radio transmission, a ground wave is a guided wave that propagates close to the surface of the Earth.

Mechanical wave

A mechanical wave is a wave that is an oscillation of matter, and therefore transfers energy through a medium. While waves can move over long distances, the movement of the medium of transmission—the material—is limited. Therefore, the oscillating material does not move far from its initial equilibrium position. Mechanical waves transport energy. This energy propagates in the same direction as the wave. Any kind of wave has a certain energy. Mechanical waves can be produced only in media which possess elasticity and inertia.

Birefringence optical phenomenon

Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are said to be birefringent. The birefringence is often quantified as the maximum difference between refractive indices exhibited by the material. Crystals with non-cubic crystal structures are often birefringent, as are plastics under mechanical stress.

Sine wave mathematical curve that describes a smooth repetitive oscillation; continuous wave

A sine wave or sinusoid is a mathematical curve that describes a smooth periodic oscillation. A sine wave is a continuous wave. It is named after the function sine, of which it is the graph. It occurs often in pure and applied mathematics, as well as physics, engineering, signal processing and many other fields. Its most basic form as a function of time (t) is:

A transverse mode of electromagnetic radiation is a particular electromagnetic field pattern of radiation measured in a plane perpendicular to the propagation direction of the beam. Transverse modes occur in radio waves and microwaves confined to a waveguide, and also in light waves in an optical fiber and in a laser's optical resonator.

Reflection (physics) change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated

Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves. The law of reflection says that for specular reflection the angle at which the wave is incident on the surface equals the angle at which it is reflected. Mirrors exhibit specular reflection.

Pockels effect appearance or change of birefringence in an optical medium by an applied electric field

The Pockels effect, or Pockels electro-optic effect, changes or produces birefringence in an optical medium induced by an electric field. In the Pockels effect, also known as the linear electro-optic effect, the birefringence is proportional to the electric field. In the Kerr effect, the refractive index change (birefringence) is proportional to the square of the field. The Pockels effect occurs only in crystals that lack inversion symmetry, such as lithium niobate, and in other noncentrosymmetric media such as electric-field poled polymers or glasses.

In plasma physics, waves in plasmas are an interconnected set of particles and fields which propagate in a periodically repeating fashion. A plasma is a quasineutral, electrically conductive fluid. In the simplest case, it is composed of electrons and a single species of positive ions, but it may also contain multiple ion species including negative ions as well as neutral particles. Due to its electrical conductivity, a plasma couples to electric and magnetic fields. This complex of particles and fields supports a wide variety of wave phenomena.

Polarizer

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.

The optical field is a term used in physics and vector calculus to designate the electric field shown as E in the electromagnetic wave equation which can be derived from Maxwell's Equations. In electromagnetic theory, the electromagnetic wave propagates such that both the magnetic field oscillation, and the electric field oscillation is perpendicular to the direction of propagation of the wave. As with any wave, the electromagnetic wave transports energy, thus the total energy density is shared between the constituent electric and magnetic fields. Since the electric field is considerably more effective at exerting forces and doing work on charges than the magnetic field, the electric field E is referred to as the optical field.

Wave propagation is any of the ways in which waves travel.

The term plane of polarization refers to the direction of polarization of linearly-polarized light or other electromagnetic radiation. Unfortunately the term is used with two contradictory meanings. As originally defined by Étienne-Louis Malus in 1811, the plane of polarization happened to coincide with the plane containing the direction of propagation and the magnetic vector; but this was not known at the time. In modern literature, the term plane of polarization, if it is used at all, more often refers to the plane containing the direction of propagation and the electric vector, because the electric field has the greater propensity to interact with matter. That propensity, together with Malus's definition and Fresnel's speculations on the luminiferous aether, led early investigators to define the "plane of vibration" as perpendicular to the plane of polarization and containing the direction of propagation.

References

  1. 1 2 Moore, Ken (2005-07-25). "What is a ray?". ZEMAX Users' Knowledge Base. Archived from the original on 2013-06-24. Retrieved 2008-05-30.

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