The key difference between plane polarized light and ordinary light is that the plane-polarized light has its vibrations occurring within them in a single plane, whereas the ordinary light has vibrations occurring within them at random angles without any plane.
Light is a type of electromagnetic radiation (EMR) having a wavelength that is detectable by the human eye. We can observe that this wavelength range is a small part of the electromagnetic spectrum.
CONTENTS
1. Overview and Key Difference
2. What is Plane Polarized Light
3. What is Ordinary Light
4. Plane Polarized Light vs Ordinary Light in Tabular Form
5. Summary
What is Plane Polarized Light?
Plane polarized light is a type of EMR having its vibrations occurring within them in a single plane. We can make a light polarized by the process of polarization. It is a property of transverse waves that are specifically the geometrical orientation of the oscillations. Usually, a transverse wave has the direction of the oscillation perpendicular to the direction of motion of the wave. E.g. guitar string. In a guitar string, the vibration direction can vary according to the plucking of the string; the direction can be vertical, horizontal, or other angles perpendicular to the string. Furthermore, the transverse waves that can undergo polarization include electromagnetic waves (including light and radio waves), gravitational waves, and transverse sound waves in solids.
Most of the sources of light are incoherent or unpolarized because there is a random mixture of waves with different spatial characteristics, frequencies, phases, and polarization states. It is easy to consider light or other EMR waves as a plane wave for understanding the polarization of EMR waves.
Figure 01: Vertically Polarized Light Wave
Plane polarized light has all of its waves having the direction of vibration. There are three major types of light polarization; linear polarization, circular polarization and elliptical polarization. Linear polarization involves the electric field of light limited to a single plane in which the propagation occurs. In the circular polarization process, there are two linear components in an electric field of light that are perpendicular to each other in a way that their amplitudes are equal, but phases are different. In this phenomenon, propagation occurs in a circular motion. Finally, in the elliptical polarization process, the electric field of light is at an elliptical propagation where the amplitude and phase difference between the two linear components are non-equal.
The methods we can use to plane polarize the light include polarization by transmission, polarization by reflection, polarization by scattering, and polarization by refraction.
What is Ordinary Light?
Ordinary light or unpolarized light is an EMR where the oscillations of all the light waves are not in a single direction. Typically, sunlight or the light emitted from a filament lamp is ordinary light. These light sources emit light from a random process in which atoms undergo changes to produce light. Therefore, light waves coming from these light sources also have their oscillations in random directions.
We can polarize the ordinary light by passing the light waves through a polarization filter. These filters contain long chains of organic molecules that are arranged in a parallel arrangement. Therefore, when light passes through this filter, it can absorb the components of electric fields in the light, which are parallel to the direction of the arrangement of the organic molecules. Similarly, the light that comes out of the polarization filter has its electric field oscillating along one direction, or simply, it is polarized.
What is the Difference Between Plane Polarized Light and Ordinary Light?
Light is a type of electromagnetic radiation (EMR) having a wavelength that is detectable by the human eye. We can polarize light using analytical techniques. The key difference between plane polarized light and ordinary light is that the plane-polarized light has its vibrations occurring within them in a single plane, whereas the ordinary light has vibrations occurring within them at random angles without any plane.
Below is a list of differences between plane polarized light and ordinary light in tabular form for side by side comparison.
Summary – Plane Polarized Light vs Ordinary Light
Light is a type of electromagnetic radiation (EMR) having a wavelength that is detectable by the human eye. We can polarize light using analytical techniques. The key difference between plane polarized light and ordinary light is that the plane-polarized light has its vibrations occurring within them in a single plane whereas the ordinary light has vibrations occurring within them at random angles without any plane.
Reference:
1. “Polarization of Light – Definition, Types, Methods, & Applications.” BYJUS, BYJU’S, 15 Oct. 2020.
Image Courtesy:
1. “Electromagnetic wave” By P.wormer – Own work (CC BY-SA 3.0) via Commons Wikimedia