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Polarization (waves)

physical science Maturity 11-13 Next article →

Polarization is a fundamental property of transverse waves. It describes the specific geometrical orientation of the oscillations. In a transverse wave, the direction of oscillation is perpendicular to the direction of travel. A simple example is a vibrating guitar string. When plucked, the string can vibrate vertically, horizontally, or at any angle. This directional movement is what we define as polarization.

Electromagnetic wave2
Electromagnetic wave2

Electromagnetic waves, like light and radio waves, are transverse. These waves consist of two coupled fields. They include an oscillating electric field and a magnetic field. These two fields always oscillate perpendicular to one another. By convention, scientists define the polarization direction by the electric field vector. The magnetic field remains at a right angle to it.

Polarisation rectiligne
Polarisation rectiligne

There are different states of polarization based on field movement. In linear polarization, the electric and magnetic fields oscillate in a single direction. This direction is perpendicular to the path of the wave. Another type is circular polarization. In this state, the fields rotate around the beam's path at a constant rate. This rotation can move in a right-hand or left-hand direction.

Polarisation state - Right-circular polarization
Polarisation state - Right-circular polarization

If the rotation follows an oval shape, it is called elliptical polarization.

Polarisation ellipse2
Polarisation ellipse2

Most light sources are unpolarized. This includes light from the sun, flames, or incandescent lamps. Unpolarized light consists of short wave trains with an equal mixture of different polarizations. This creates a random mixture of spatial characteristics and phases. You can create polarized light by using a polarizer. A polarizer is a tool that allows only one polarization to pass through.

CircularPolarizer
CircularPolarizer

Light also becomes partially polarized when it reflects off a surface at an angle.

Mudflats-polariser
Mudflats-polariser

Quantum mechanics provides a different way to view these waves. In this field, electromagnetic waves are seen as streams of particles called photons. Polarization is determined by a quantum property called spin. A photon can have one of two possible spins. It can spin in a right-hand sense or a left-hand sense. Circularly polarized waves are made of photons with only one type of spin. Linearly polarized waves are a superposition of both right and left spin states. These states are synchronized to produce an oscillation in a single plane.

Wave Polarisation
Wave Polarisation

Certain materials change how light behaves based on its polarization. Some materials exhibit birefringence, dichroism, or optical activity. These properties allow them to affect light differently depending on its orientation. Birefringence can be seen when stress is applied to certain objects.

Birefringence Stress Plastic
Birefringence Stress Plastic

This can change the paths taken by light vectors. Understanding these interactions is vital for creating advanced optical filters and lenses.

Polarization is a critical parameter in many scientific fields. It is essential for studying optics, seismology, radio, and microwaves. It plays a major role in modern communication technologies. For example, wireless and optical fiber telecommunications rely on polarization. Radar systems and lasers also depend on these wave properties. Even the study of earthquakes uses polarization to understand how waves move through the Earth.

Cross linear polarization
Cross linear polarization
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🖼️ Images & Media (23)
File:Polarizacio.jpg
Polarizacio.jpg
File:Cross_linear_polarization.gif
Cross_linear_polarization.gif
File:Electromagnetic wave2.svg
Electromagnetic wave2.svg
File:Polarisation rectiligne.gif
Polarisation rectiligne.gif
File:Polarisation state - Linear polarization parallel to x axis.svg
Polarisation state - Linear polarization...
File:Polarisation state - Linear polarization oriented at +45deg.svg
Polarisation state - Linear polarization...
File:Polarisation state - Right-elliptical polarization A.svg
Polarisation state - Right-elliptical...
File:Polarisation state - Right-circular polarization.svg
Polarisation state - Right-circular...
File:Polarisation state - Left-circular polarization.svg
Polarisation state - Left-circular...
File:Wave Polarisation.gif
Wave Polarisation.gif
File:Rising circular.gif
Rising circular.gif
File:Polarisation ellipse2.svg
Polarisation ellipse2.svg

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