Wave-particle Duality

Albert Einstein proposed the Quantum Theory of Light. It describes how light travels in energy bundles. 

A photon is the name given to each bundle. Every photon carries a certain amount of energy. This is equal to the product of that photon’s oscillation frequency and Planck’s constant. The wave-particle duality concept of quantum physics states that, depending on the circumstances of the experiment, matter and light display both wave and particle characteristics. It’s a complicated subject, but one of the most fascinating in physics.

Wave Theory of Light

Diffraction and interference are two separate types of wave behavior. Light, according to James Clerk Maxwell, is an electromagnetic wave. It moves through space at the speed of light. The frequency of light is proportional to its wavelength, as seen in the equation below.

V=c

Here, 

V is known as frequency

C= Speed of Light

= Wavelength

Wave Particle Duality in Light

Christiaan Huygens and Isaac Newton offered opposing ideas for the behavior of light in the 1600s. Huygens suggested a “wave” (particle) explanation of light, whereas Newton proposed a “corpuscular” (particle) theory. 

Huygens’ hypothesis had several problems matching observations, and Newton’s prestige helped provide support to his theory, therefore Newton’s theory dominated for over a century.

Complications occurred for the corpuscular theory of light in the early nineteenth century. For one thing, diffraction had been seen, which it had problems fully explaining. Thomas Young’s double slit experiment revealed clear wave activity, implying that the wave theory of light prevailed over Newton’s particle theory.

A wave must travel through some form of medium in order to propagate. Huygens offered luminiferous aether as the medium (or in more common modern terminology, ether). When James Clerk Maxwell quantified a set of equations (called Maxwell’s laws or Maxwell’s equations) to explain electromagnetic radiation (including visible light) as the propagation of waves, he assumed exactly such an ether as the propagation medium, and his predictions matched experimental results.

The wave theory had a flaw in that no such ether had ever been discovered. Furthermore, astronomical findings in star aberration by James Bradley in 1720 suggested that ether would have to be stable in relation to a moving Earth. Attempts to directly detect the ether or its movement were made during the 1800s, culminating in the famous Michelson-Morley experiment. As the twentieth century began, they all failed to discover the ether, resulting in a big controversy.

With photons, the ether was no longer required for propagation, but the strange mystery of why wave behavior was observed remained. The quantum fluctuations of the double slit experiment, as well as the Compton Effect, seemed to support the particle interpretation.

Wave-Particle Duality in Matter

The bold de Broglie hypothesis, which expanded Einstein’s work to tie the measured wavelength of matter to its momentum, attempted to answer the question of whether such duality existed in matter. Experiments in 1927 verified the concept, earning de Broglie the Nobel Prize in 1929.

Matter, like light, appeared to have both wave and particle qualities when the conditions were correct. Massive objects, of course, have extremely short wavelengths, so short that thinking of them as waves is really pointless. The wavelength can be observable and significant for small objects, as demonstrated by the double slit experiment with electrons.

Significance of Wave-Particle Duality

The wave-particle duality is significant because it allows all aspects of light and matter to be explained using a differential equation that depicts a wave function, usually in the form of the Schrodinger equation. Quantum physics is based on the ability to explain reality in terms of waves.

The most prevalent explanation is that the wave function represents the chance of detecting a specific particle at a specific location. 

These probability equations can diffract, interfere, and display other wave-like qualities, resulting in a final probabilistic wave function that does as well. Particles are distributed according to probability principles and display wave features as a result.

While mathematics provides accurate predictions despite its complexity, the physical meaning of these equations is significantly more difficult to grasp. A fundamental issue of contention in quantum physics is attempting to explain what the wave-particle duality “actually implies.” Many theories have been proposed to explain this, but they are all constrained by the same set of wave equations and must eventually explain the same experimental results.

Conclusion

The kinetic energy of photoelectrons is unaffected by the light intensity that induces the photoelectric effect.

As the frequency of light rises, the greatest kinetic energy of photoelectrons increases.Light possesses both particle and wave qualities. From one place to the next, light travels in waves. However, it obeys the boundary conditions of a particle carrying energy, momentum, and angular momentum at the locations where it is emitted or absorbed.

Planck hypothesized that light energy is proportional to frequency, and Planck’s constant is the constant that connects the two (h). Albert Einstein’s finding that light is made up of discrete quanta of energy known as photons was aided by his study.