Home | Physics | What is Light in Physics?-Electromagnetic Spectrum, Colour, And Theories

What is Light in Physics?-Electromagnetic Spectrum, Colour, And Theories

August 21, 2022
written by Adeel Abbas

Light or visible light is the electromagnetic radiation within the portion of the spectrum that is perceived by the human eye.

What is light in physics?

Light is electromagnetic radiation that travels at 186,282 miles per second (299,792 kilometers per second). Light is composed of photons, which are particles of light. Photons have no mass and travel at the speed of light. When we look at the sun, we are seeing the light emitted by billions of stars that are millions of years old.

When light hits an object, some of the light bounces off the object while the rest passes right through. The amount of light that bounces back is dependent on the material of the object. Objects that reflect light well are shiny objects. Shiny objects are often metal or glass.

Metal reflects light really well, so if you shine a flashlight on a metal surface, you should see lots of reflections. Glass does not reflect much light, so if you shine the flashlight onto a piece of glass, you won’t get many reflections.

The electromagnetic spectrum of Light

The visible light region consists of quanta that are at the lower end of the energies that are capable of causing electronic excitation within the molecule, which leads to changes in the bonding or chemistry of the molecule.

EMR becomes invisible to humans at the lower end of the visible light spectrum because it no longer has enough individual energy to cause a long-term change in the visual molecule in the human retina.

Above the range of visible light, ultraviolet light is invisible to humans because it is absorbed by the internal lens of the eye and the cornea. The rods and cones located in the retina of the human eye can’t detect the very short ultraviolet wavelength and are damaged by it. The same chemical way that humans detect visible light can be used to detect ultraviolet in many animals with eyes that do not require glasses.

Colour of light

The color of light is determined by its wavelength. Red light has a longer wavelength than blue light. When we look at the sky, we see white light. White light contains all colors of light. We call the different colored lights that make up white light “colors”.

In order to see the full range of colors, our eyes need to detect all wavelengths of light. Our eyes are sensitive to only certain parts of the spectrum. These parts are called bands. Each band detects a specific wavelength of light. Humans can see five bands of light. These bands are called the visible spectrum. The human eye cannot detect light outside these bands.

What is optics?

The study of light and the interaction of light and matter is referred to as optics. There are many clues as to the nature of light as a result of the observation and study of optical phenomena such as rainbows.

Light sources

There are substances that produce light when they are illuminated by more energetic radiation. Light is emitted by some substances after they have been exposed to more energetic radiation. phosphorescence is what this is known for. Phosphorescent materials can be excited by bombarding them with subatomic particles. CRT Television sets and computer monitors have this mechanism in them.

Historical theories about light

 These are some historical theories about light

  • Classical Greece and Hellenism
  • Classical India
  • Descartes
  • Particle theory
  • Wave theory
  • Electromagnetic theory
  • Quantum theory

Use for light

Sunlight provides the energy that green plants use to create sugars in the form of stars, which are then released into the living things that digest them. Most of the energy used by living things is provided through the process of photosynthesis.

bioluminescence is a process in which some species of animals produce their own light. Vampire squid uses light to hide from their prey, and fireflies use light to locate their mates.