Particle nature of light

Introduction

In 1905, Albert Einstein published a paper explaining the photoelectric effect. According to Einstein, light is a beam of particles whose energies are related to their frequencies according to Planck’s formula. This was the first time that the particle nature of light had been acknowledged. Continuing our exploration of the subject, we will explore the particle nature of light, its features, and other related sub-topics in more detail in this article.

Light characterised by wave

In energy transmission via space, a wave is a periodic oscillation. Because light is a sort of electromagnetic wave, according to the wave nature of light theory, it is classified as such. Humans may observe this wave. With the help of tests on diffraction and interference, the particle nature of electromagnetic radiation was demonstrated.

Either incandescent or luminescence is used to generate light in a given situation. When a matter is heated to a high temperature, it emits light. Yet, when electrons are stimulated to a low energy level, they emit light as they fall to a lower energy level (luminescence).

Particle nature of light 

When we talk about particles, we’re talking about little pieces of stuff. Although light is made up of particles, we refer to them as photons since they are light particles. When Sir Isaac Newton used a prism to split sunlight into multiple colours, the perimeter of the shadows he cast was exceedingly crisp and distinct, leading him to conclude, in 1700, that light was made up of particles.

As an elementary particle and a quantum of light, photon is defined thus: Using the equation E = hv, we can figure out how much energy a photon has. Energy is denoted by E, while h is Planck’s constant and v is the frequency of photons. In this case, raising the intensity of light indicates that we have increased the number of photons that pass an area in a certain amount of time. Another advantage of photons is that they have no mass yet are considered stable subatomic particles. A photon may transmit energy to a different particle during an interaction.

Photons

Essentially, a photon is a subatomic particle of light. The particle of light is called a photon or quanta.

• The equation E = hv describes the energy of a photon. Because of this, it has the same momentum and speed as light.
• The momentum p and energy E of every photon with frequency v are the same regardless of the intensity of the radiation.
• As light intensity increases, the number of photons passing a specific region per unit time increases proportionally. Radiation energy is not affected by this factor.
• Electric and magnetic fields do not affect a photon’s behaviour. 
• Electricity is not a factor in this case.
• A photon has no mass, i.e. it has no gravitational attraction to any other particle.
• In terms of stability, it is an excellent candidate for use in physics.
• The emission or absorption of radiation can result in the creation or destruction of photons, respectively.
• During a photon-electron collision, both total energy and momentum are preserved.
• Without an external energy source, a photon can’t decay.
• During contact with other particles, the energy of a photon can be transmitted.
• Unlike electrons, which have spin (±½), a photon has a spin ±1. Its spin axis runs parallel to the direction in which it is travelling. This feature of photons allows light to be polarised in the first place.

Difference between wave and particle

It is a hypothesis that light has both a wave and a particle nature, which defines how light behaves in both ways. There is a significant difference between the wave and particle natures of light in that the wave nature of light explains that light can act as an electromagnetic wave. In contrast, the particle nature of light explains that light is made up of particles known as photons, which are tiny particles.

Photoelectric effect 

Luminous illumination causes metal to emit electrons from its valence shell, which results in the photoelectric effect of light being induced. Photographic electrons are released when light strikes them; this phenomenon is called photoemission or photoelectron essence. If we believe light to be a wave, we will be unable to explain this phenomenon; but if we consider light to be a particle, we will explain the photoelectric effect.

Wilhelm Ludwig Franz Hallwachs initially observed the photoelectric effect, and Heinrich Rudolf Hertz confirmed it. Using the quantum nature of light and the theory of relativity, Einstein described this occurrence. As a result of his work on the photoelectric effect, Einstein received the Nobel Prize in Physics in 1921.

Working principle of the photoelectric effect

If you illuminate a metal surface with light, you will see the photoelectric effect take place. When light falls on a metal surface, it will cause photoemission, which will result in photoelectrons being emitted from the metal surface.

Conclusion

Essentially, we learned about the dual nature of light – wave and particle nature – in this article. Photons, the subatomic particles that make up light, were first introduced to us. Even though they are packed with energy and have a certain amount of momentum, photons have no rest mass.