In nature, the luminous energy manifests itself as light. It originates from bodies that are capable of emitting light, and we refer to these bodies as light sources. The sun is the most excellent source of light energy.
For over a hundred years, there was a heated argument on whether the light was a particle or wave. After much discoveries and proofs, in the 20th century, physicists came to believe that light could be both a particle and a wave at the same time.
Optical phenomena are any observable events that derive from the interaction of light and matter. See also set of optical topics and optics. A mirage is a typical example of an optical phenomenon. Common optical phenomena in many cases are as a result of interaction of light from sunlight or moon with the atmosphere, clouds, water, dust, and other particulates. One common example may be the rainbow, when light from sunlight is reflected and refracted by water droplets. Some phenomenon, like the green ray, is so rare they’re sometimes considered to be mythical. Others, such as Fata Morganas, are commonplace in favored locations. Optical phenomena include those arising from the optical properties of the atmosphere.
Behaviour of Light
Light undergoes many phenomena, and a few of the most prominent are give below:
● Absorption of light
Absorption of light occurs when matter captures electromagnetic radiation, converting the energy of photons to internal energy. If a material absorbs all the light that it receives, the object will appear black. On the contrary, if it reflects all the incident light, it will appear white. If the object absorbs some components of white light and reflects the rest of the light, then the colour of the object be will be the result of the colour of the reflected light. If it reflects red, then the object appears red, likewise, if the colour blue is reflected, then the object appears blue.
● Reflection of light
The change in direction that light rays suffer when it collides the surface of another medium is known as the reflection of light. There are two laws of reflection, and they state the following:
1. The angle of incidence is always equal to the angle of reflection.
2. The incident ray, the reflected ray and the normal all lie in the same plane.
The reflection of light can be categorized into two types as specular reflection and diffuse reflection based on the texture of the surface from which the light reflects.
● Dispersion of Light
Light splits into different colour components when it passes through a prism. This phenomenon is known as the dispersion of light. A prism consists of two plane surfaces that are inclined at an angle. A white light passing through a prism splits into seven colours as “violet, indigo blue, green, yellow, orange and red”.
● Refraction of Light
We use the term refraction to describe the phenomenon which results in the change in the direction of a wave passing from one medium to another. Refraction is the most commonly observed phenomenon; waves such as sound waves and water waves also experience refraction. The formation of a rainbow is an example of refraction. Here, as the sun rays pass through the raindrops in teh atmosphere, the rains bend which results in a rainbow.
● Relativistic Doppler Effect for Light
Light waves from a moving source experience Doppler effect resulting in either a redshift or a blue shift in the light’s frequency. A light source moving away from the listener would provide an fL that is less than the source. In the visible spectrum, this causes a shift towards the red end of the spectrum and is called redshift. When light moves toward the listener, then fL is higher than fs. This results in a shift towards the high-frequency end of the spectrum and this frequency shift is known as a blue shift.
