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What is polarization of light

To understand the polarization of light, we first need to develop a suitable visual concept of electromagnetic waves. To do this, we can examine how a vibrating electric charge generates electromagnetic waves. A stationary charge is surrounded by an electric field. This field can be imagined as lines of force radiating from the charge in straight lines in all directions. If the charge is suddenly displaced a short distance, while the lines of force remain attached to the charge, the displacement propagates along the lines of force at the speed of light. In this way, the vibrating charge generates waves that propagate along the lines of force, much like the ripples on a taut string. These waves are accompanied by magnetic fields, but the form of these fields is not necessary to examine here. The above image of electromagnetic waves clearly illustrates that the electric vector components of such waves lie in a plane defined by the direction of propagation and the direction of the charge vibration. Light whose electric vector components all lie in the same plane of vibration is called linearly polarized light.

The angle between the plane of vibration and a particular direction (such as vertical) is called the angle of polarization. Most light sources emit unpolarized light, a light wave whose electric vector components have no definite direction. Linearly polarized light can be produced by passing unpolarized light through a polarizing filter, such as a suitable crystal or crystal array (polarizer) that selects the electric vector component of the light wave in one plane.

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