Light: Properties

The properties of light are the characteristics that define how light behaves and interacts with matter. Some of the important properties of light are:

- Reflection: Reflection of light is the phenomenon where light bounces off a surface and changes direction. 

- Refraction: Refraction of light is the phenomenon where light changes direction as it passes from one medium to another. This bending of light is caused by the change in speed of light as it moves from one medium to another 1. The amount of bending depends on the angle at which the light enters the new medium and the difference in the refractive indices of the two media

- Diffraction: Light spreads out when it encounters an obstacle or a slit that is comparable to its wavelength. Diffraction of light is a phenomenon where light waves bend around corners or obstacles and spread out, creating a pattern of bright and dark regions. When light waves encounter an obstacle, such as a slit or a small opening, they diffract and bend around the edges of the obstacle, creating a diffraction pattern on a screen placed behind the obstacle.

- Interference: Light waves can add up or cancel out each other when they overlap, creating patterns of bright and dark spots. Interference of light is a phenomenon that occurs when two waves superpose to form the resultant wave of the lower, higher, or same amplitude. The most commonly seen interference is the optical interference or light interference. This is because light waves are generated randomly by most of the sources. This means that light waves coming out of a source do not have a constant amplitude, frequency, or phase.

- Scattering: The redirection of light by small particles in the atmosphere or in a medium. Scattering can affect the color and intensity of light. For example, blue light is scattered more than red light by air molecules, which is why the sky is blue and the sun appears reddish at sunrise and sunset.

- Polarization: Polarization of light is a phenomenon caused due to the wave nature of electromagnetic radiation. Light is the interaction of electric and magnetic fields travelling through space. The electric and magnetic vibrations of a light wave occur perpendicularly to each other. The electric field moves in one direction and the magnetic field in another ‘perpendicular to each other. So, we have one plane occupied by an electric field, another plane of the magnetic field perpendicular to it, and the direction of travel is perpendicular to both. 

These electric and magnetic vibrations can occur in numerous planes. A light wave that is vibrating in more than one plane is known as unpolarized light. The light emitted by the sun, by a lamp or a tube light are all unpolarised light sources.

The process of transforming unpolarized light into polarized light is known as polarization.

- Dispersion: Light can be split into its component colors when it passes through a prism or a raindrop, creating a spectrum or a rainbow. Dispersion of light is the phenomenon of splitting a beam of white light into its constituent colors. When white light passes through a prism, it bends at different angles depending on the wavelength of the light. The shorter the wavelength, the more the light bends. This causes the white light to separate into a spectrum of colors, ranging from violet (the shortest wavelength) to red (the longest wavelength). Dispersion of light can also occur when light travels through other transparent materials, such as water droplets or glass lenses.

- Absorption: Absorption is when light is absorbed by atoms or molecules in a medium, which can cause them to emit light of a different wavelength or transfer energy to other particles. It is the process by which a material absorbs photons of electromagnetic radiation and converts them into internal energy.

- Emission: Light is emitted by atoms or molecules when transition is from a higher to a lower energy state, which can produce spectra of discrete or continuous wavelengths.  Emission of light is the process by which matter emits electromagnetic radiation. The emission can be spontaneous or stimulated, depending on the energy state of the atoms or molecules involved. Spontaneous emission occurs when an excited atom or molecule returns to a lower energy state and releases a photon. Stimulated emission occurs when an incoming photon causes an excited atom or molecule to emit a photon of the same frequency, phase, and direction as the incoming photon.

Points to Ponder:

Why light has these properties?

Are these properties just frivolous phenomenon? 

Are these just isolated or part of something grander and unified?





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