# Models of Light

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Usually light means visible light. Light is electromagnetic radiation having wavelengths between 380 nm to 780 nm that can be detected by the human eye. Light has different models. Light can not be described in one way, its nature is complicated. Sometimes, light can be described as a particle, sometimes it acts as a wave. These 2 are the main two models of light. Besides, light can be described by the ray model too. Thus, light has one more model, in total, it's 3.

Scientist Newton's corpuscular theory of light states that light consisted of particles that traveled in straight lines. Another scientist Huygens argued with this theory (corpuscular theory) and said that if light acts like a particle then when light beams crossed, the particles would collide and cancel each other. Huygen proposed another model, the wave model of light.

## Three Models of Light

Light has three models. They are termed as
• The Wave Model
• The Ray Model
• The Photon Model/The Particle Model/Quantum Model

## The Wave Model of Light

The wave model of light's proposed by Huygens. He argued with Newton's theory that says, "light is made of particles." As a wave, light can be described by c=f\lambda where,
c =  velocity of light (in meter per second)
f = frequency (in Hertz) and
\lambda = wavelength of light (in meters)

The wave model of light describes how light waves spread out and how the superposition of multiple light waves causes interference. These cannot be described by other models.

## The Ray Model of Light

In optics, a ray is an idealized model of light, obtained by choosing a line that is perpendicular to wavefronts of the actual light and that points in the direction of energy flow. Rays are used to model the propagation of light through an optical system. Ray model describes how light travels in straight lines, it will explain how the mirrors work, how the lenses work.

## The Quantum Model/Photon Model of Light

This photon model is an important part of Quantum Physics. From Newton's theory, we get an idea about this. Light consists packet of photons or energy that can only interact with the atoms and molecules of matter by being absorbed or emitted.

## Comparison Between the Wave Model and the Particle Model of Light

We know that Isaac Newton found that prism splits sunlight into seven different colors. The periphery of the shadows it created was extremely sharp and clear, which led him to describe the particle nature of light. On the contrary, Francesco Maria Grimaldi observed the diffraction of light and stated that light has the behavior of waves. Huygens said the same.

The wave model of light is a concept that states light behaves as an electromagnetic wave whereas the particle model states that light consists of particles that are called photons. Light can propagate through a vacuum as the wave nature. On the other hand, in particle nature, light consists of elementary particles and these particles/photons carry the energy.
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