The key difference between wave and particle nature of light is that the wave nature of light states that light can behave as an electromagnetic wave, whereas the particle nature of light states that light consists of particles called photons.
Wave-particle duality is a concept in quantum mechanics. It states that all the particles and quantum entities have not only a wave behaviour but also a particle behaviour. The classical “wave” and “particle” concepts cannot completely describe the behaviour of quantum-scale objects; thus, the wave-particle duality theory is very important for this.
CONTENTS
1. Overview and Key Difference
2. What is Wave Nature of Light
3. What is Particle Nature of Light
4. Side by Side Comparison – Wave vs Particle Nature of Light in Tabular Form
5. Summary
What is Wave Nature of Light?
A wave is a periodic oscillation by which energy is transmitted through space. Wave nature of light states that the light is a type of electromagnetic wave. Humans can see this wave. The first illustration of the wave nature of light was using the experiments on diffraction and interference.
The production of light is from one of these two methods – incandescence or luminescence. Incandescence is the emission of light from hot matter while luminescence is the emission of light during the fall of excited electrons to the ground energy level.
Figure 01: An Illustration of Electromagnetic Waves
Light, as same as all other electromagnetic waves, can travel through a vacuum. Also, it is periodic, which means it is repeated regularly in both space and time. Similar to other waves, light also has a wavelength (the distance between two waves), frequency (the number of waves that occur per unit time) and a speed (around 3 x 108 m/s).
What is Particle Nature of Light?
A particle is a portion of matter. However, in the particle nature of light, we call light particles photons. In 1700, Sir Isaac Newton stated that light is a bunch of particles because when he used a prism to split sunlight into different colours, the periphery of the shadows created was extremely sharp and clear.
Figure 02: Conceptual Animation of the Dispersion of Light as it Travels through a Prism
A photon is an elementary particle and a quantum of light. We can calculate the energy of a photon via the equation E = hv where energy is E, h is the Planck’s constant and v is the speed of light. Here, increasing the intensity of light means that we have increased the number of photons crossing an area per unit time. Moreover, a photon has no mass, but it is a stable particle. A photon can transfer its energy to another particle during an interaction.
What is the Difference Between Wave and Particle Nature of Light?
Wave-particle duality is a theory which describes that light has both wave and particle nature. The key difference between wave and particle nature of light is that the wave nature of light explains that light can behave as an electromagnetic wave, whereas the particle nature of light explains that light consists of particles called photons.
Moreover, according to the scientists, Francesco Maria Grimaldi and Sir Isaac Newton, who first noted these two natures of light, Francesco Maria Grimaldi observed the diffraction of light and stated that light has behaviour of waves, while Sir Isaac Newton found that when a prism splits sunlight into different colours, the periphery of the shadows created was extremely sharp and clear which led him to state the particle nature of light.
Summary – Wave vs Particle Nature of Light
Wave-particle duality theory is a modern theory that states light has both wave and particle behaviours. The key difference between wave and particle nature of light is that the wave nature of light describes that light can behave as an electromagnetic wave, whereas the particle nature of light describes that light consists of particles called photons.
Reference:
1. “The Wave Nature of Light.” Chemistry LibreTexts, Libretexts, 1 June 2019, Available here.
Image Courtesy:
1. “Electromagnetic waves” By DECHAMMAKL – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Light dispersion conceptual” By LucasVB – Own work (Public Domain) via Commons Wikimedia