What is Light Energy

Let us know today what is Light Energy

What is light energy?

Light Energy Definition:

Light is the only energy form visible to the human eye, light energy can be defined in two ways: Light is made up of massive energy packets known as photons. Photons are energy packets that carry a certain amount of light energy depending on the wavelength. Light energy refers to the range of electromagnetic energy which includes gamma rays, X-rays, visible light, etc.
The visible range of the electromagnetic spectrum is commonly referred to as light.

Nature of Light:

In the 17th century there were two views regarding the nature of light.

particle nature light

Isaac Newton believed that light is made up of tiny discrete particles called corpuscles. According to him, these tiny particles were emitted by hot objects like the Sun or fire and traveled in a straight line with a finite velocity and had impulses. This became known as Newton’s corpuscular theory of light.

wave nature of light

Christiaan Huygens claimed to disprove Newton’s corpuscular theory by proposing a wave theory of light. According to him light was made up of waves vibrating vertically up and down in the direction of its propagation. This became known as the ‘Huygens’ principle.’

In the early 19th century, an English physicist Thomas Young conducted an experiment showing light from a point source after passing through two slits, placed at an appropriate distance Creates an interference pattern on the screen. This is known as Young’s double-slit experiment, which advocated the wave nature of light while supporting the Huygens theory.

James Clark Maxwell laid the foundation for modern electromagnetism, which described light as a transverse wave oscillating magnetic and electric fields at 90° from each other. The representation of light as transverse waves contradicted Huygens, who believed that the light wave was longitudinal.

Albert Einstein revived particle theory by introducing the concept of the photon. Einstein’s experiment, known as the photoelectric effect, showed that light consisted of discrete bundles or quanta of light energy, called photons.

The phenomenon of interference and diffraction can be explained simply by considering it as a wave of light. In comparison, the photoelectric effect could be explained by the particle nature of light.
This overwhelming dilemma about the nature of light was resolved by the foundations of quantum mechanics which established the wave–particle duality on the nature of both light and matter. 

Properties of Light:

Light Interaction:

Light waves interact with matter in different ways:

reflection of light

– When a light wave bounces off the surface of a substance through its past propagation, the process is called reflection. For example, the image formed over a calm pond/lake.

absorption of light

When a material absorbs the energy of a light wave falling on it, this process is called absorption. For example, glow-in-the-dark plastic, which absorbs light and re-emits it as phosphorescence.


When a light wave passes through a material, this process is called transmission. For example, light is passing through a glass window.


Interference refers to the phenomenon in which two light waves move to produce a resultant wave that can have lower, higher or equal amplitudes. Constructive and destructive interference occurs when the waves of interaction are coherent with each other, either because they share the same source or because they have the same or comparable frequency.


Refraction is an important behavior exhibited by light waves. When light waves deflect from their original path, they enter a new medium. Light exhibits different speeds in different transmitting materials. The change in speed and degree of deviation depends on the angle of the incoming light.


Distraction is defined as the bending of light waves around the corners of the aperture, in its geometric shadow region. The distracting barrier, or aperture, becomes the secondary source of the propagating light wave. One of the most common examples of diffraction is the formation of rainbow patterns on a CD or DVD. Closely spaced tracks on a DVD or CD serve as diffraction gratings, creating patterns when light falls on it.

What is Light Energy


The dispersion of light refers to the phenomenon of splitting of white light into its optical colors (.ie VIBGYOR) when passing through a glass prism or similar objects. For example, the formation of a rainbow due to the diffraction of sunlight by raindrops like prisms.

type of light

  • Light as a whole refers to electromagnetic radiation of every wavelength.
  • The wavelength of electromagnetic radiation can be classified as
  • Radio wave ~ [10 5 – 10 -1 m]
  • Microwave ~ [10 -1 – 10 -3 m]
  • infrared wave ~ [10 -3 – 0.7 x 10 -6 m]
  • Field of view (what we perceive as light) ~ [0.7 x 10 -6 – 0.4 x 10 -6 m]
  • Ultraviolet waves ~ [0.4 x 10 -6 – 10 -8 m]
  • X-ray ~ [10 -8 – 10 -11 m]
  • Gamma rays ~ [10 -11 – 10 -13 m]
  • The working of electromagnetic radiations is based on its wavelength.

frequency and wavelength of light

radio waves :

A radio wave is an electromagnetic wave with a frequency between 20 kHz and 300 GHz and is known for use in communication technologies, such as mobile phones, television, and radio. These devices accept radio waves and convert them into mechanical vibrations to produce sound waves.


Microwave is electromagnetic radiation with a frequency between 300 MHz and 300 GHz. Microwaves have a wide variety of applications, including radar, communications and cooking.

Infrared Waves:

Infrared wave is electromagnetic radiation with a frequency between 300 GHz and 400 THz, lnfrared waves find their application in heating food and television remotes, fiber optic cables, thermal imaging cameras, etc.

Visible Light :

Visible light is electromagnetic radiation with a frequency between 4 × 10 14 8 × 10 up to 14 hertz (Hz). The reason the human eye sees only a specific range of frequencies of light is because those certain frequencies excite the retina in the human eye.

Ultraviolet rays:

Ultraviolet light is electromagnetic radiation with a frequency between 8 × 10 14 and 3 × 10 16 hertz (Hz) ultraviolet radiation is used to kill germs, sterilize medical equipment, treat skin problems, etc.


X-rays are electromagnetic radiation with a frequency between 3 × 10 19 and 3 × 10 16 Hz, X-rays are used to eliminate cancer cells in X-ray machines etc.

Gamma Rays:

Gamma-rays are electromagnetic radiation with frequencies higher than 10 to 19 hertz (Hz). Gamma rays are used to kill germs, sterilize medical equipment and food.

examples of light energy

source of light

Light sources can be classified into two basic types: Luminescence and Incandescence.


Incompatibility encompasses the vibrations of all the atoms present. When atoms are heated to very high temperatures, the resulting thermal vibrations are released in the form of electromagnetic radiation. Incandescent light or “black body radiation” is created when light is emitted from a hot solid. Depending on the temperature of the material, the photons released vary in their color and energy. At low temperatures, the material produces infrared radiations.

In black body radiation, the peak shifts to shorter wavelengths with an increase in temperature, as it moves towards the ultraviolet range of the spectrum, producing a red and then white and finally an off-white color. Is.
Incandescent lighting is the most commonly used lighting. This includes the sun, light bulbs and fire.
Fire triggers chemical reactions that release heat, causing the material to reach high temperatures and eventually causing gases and the material to incinerate. Light bulbs, on the other hand, produce heat due to the passage of electric current through a cable. Incandescent light bulbs emit about 90% of their energy in the form of infrared radiations and the rest in the form of visible light.


Luminescence involves only electrons and usually occurs at a lower temperature than incandescent light.
Luminescent light is created when an electron emits a part of its energy in the form of electromagnetic radiation. When an electron jumps to a lower energy level, a certain amount of light energy is released in the form of light of a specific color. Normally, to maintain a constant luminance, a constant push is needed to push the electrons to a higher energy level so that the process continues.
For example, neon lights generate light through electroluminescence, which involves a high voltage {push}, which excites gas particles and eventually results in light emission.

How does light travel?

Light practically travels as a wave. Although according to geometrical optics, light is modeled to travel in rays. Light can be transmitted from a source to a point in three ways:

  • It can travel directly through a vacuum or empty space. For example, the travel of light from the Sun to the Earth.
  • It can travel through various mediums, such as air, glass, etc.
  • It can travel after being reflected, such as a mirror or a still lake.

Light Energy vs Electron Energy

electron energylight energy
• Electrons have mass energy at rest, that is, the energy corresponding to their mass. The rest energy of an electron can be calculated using Einstein’s equation E = mc2 .

• When the electron changes its energy level by moving from a higher energy state to a lower energy state, it emits photons.
• Light energy is in the form of small massless energy packets called photons. The amount of energy in a photon depends on the wavelength of the light. E = Hc /

• When photons with a sufficient amount of light energy fall on a material, the electrons absorb the energy and escape from the material.
What is Light Energy

use of light energy.

Light has its applications in every aspect of life. Without light energy, it was impossible for us to survive.
Some of the essential applications of light energy in our life are as follows:

  • Light allows vision. A specific range of wavelengths of light provides the right amount of energy needed to stimulate chemical reactions in our retinas to support vision.
  • Light energy allows plants to produce food through the process of photosynthesis.
  • Light energy is used as a source of power in satellite and space technologies.
  • Solar energy is used for various domestic and industrial activities.
  • Light energy (electromagnetic radiation) is used in the telecommunications industry.
  • Light energy is also used for many medical treatments.
Scroll to Top