We can simply explain the dual nature of light as the ability of light to behave like a particle or like a wave. Before we understand the previous statement, we will need to look at the definition of light, waves, and particles.
What is Light in Physics?
Light is defined as electromagnetic radiation that is noticeable to the human eye. When you raise your head up, you will be able to see the ever-shining sky. We use our eyes to watch our favorite movies. With our eyes, we can be able to play chess game. The knowledge of the behavior of light helps us to see and cherish the world around us.
The knowledge of optics helps us to provide relief to people that are having problems with their eyes. Instruments like sunglasses to prevent sun rays, and medicated eyeglasses were birthed by the knowledge of light.
We also have optical devices like microscopes to assist in viewing very tiny objects, and cameras to capture memorable moments in our lives. Light is very special because it helps us to see and identify objects.
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What is Wave in Physics?
A wave is a disturbance that travels through a medium and transfers energy from one point to another, without any permanent displacement of the medium itself.
A wave motion is a process of transferring a disturbance (in form of kinetic energy) from one point to another in a medium without any transfer of the particles of the medium.
What is a Particle in Physics?
In physics, we can say that particle is a localized object that shows certain physical properties such as mass, charge, density, spin, or volume. Particles are the foundation of matter.
We know that matter is anything that has mass and can occupy space. Matter consists of three states which are solids, liquids, and gas. These states of matter were made up of particles.
There are two categories of particles and they are:
- Elementary particles: These particles are indivisible and cannot be broken down into smaller particles. For example, some of the elementary particles are quarks, lepton, and gauge bosons.
- Composite particles: They are made up of two or more particles. Examples of composite particles include atoms (protons, neutrons, electrons), and mesons (quarks and antiquarks).
Fundamental forces such as gravity, electromagnetic force, weak force, and strong force help particles to interact with each other. The interactions of these particles are mediated by force carriers otherwise known as the exchange of particles.
What is the Dual Nature of Light?
The dual nature of light explains the ability of light to behave as a wave or as a particle. This is due to valid experiments that show light can behave as a particle, and at the same time it can also behave as a wave.
Experiments like electron diffraction indicate that light can exist as a wave. While the photoelectric effect and Compton effect experiments show that light has a nature of a particle.
What is Electron Diffraction?
Electron Diffraction is a result of the diffraction of a beam of light due to a crystal or other regular lattice structure.
What is the Photoelectric Effect?
The photoelectric effect is the process whereby electrons are emitted from the surface of a metal when light is shown on it. It’s the liberation of photons from the surface of the metal.
What is Compton’s Effect?
Compton’s scattering refers to the scattering of X-rays or gamma rays by matter, such as electrons in a material. It explains that when a single X-ray photon collides with a free electron, the electron recoils off as though it were a perfectly elastic sphere.
The experiment was first carried out in 1923 by an American physicist known as Arthur Compton.
Explanation of the Dual Nature of Light
Here is a simple way to explain the dual nature of light. We all know that there are so many things we can do with a ball. We can either throw the ball in the air or roll the ball on the floor.
Now let us replace the ball with light and the two scenarios “of throwing and rolling” with waves and particles respectively.
When light behaves like a wave, it can travel through things like air, water, and even space. Additionally, light can also bear different colors like the rainbow.
Therefore, once light behaves like a particle, we refer to that light as photons. We cannot see photons with our eyes because of their size (very small).
Therefore, light has the nature of a wave according to electron diffraction. It can also behave as a particle according to the photoelectric effect.
The above statement explains the dual nature of light to exist as a wave or as a particle. Light can travel straight due to its particle nature and can also bend due to its wave nature.