[Physics Class Notes] on Wave Particle Duality Pdf for Exam

Wave-particle duality can be explained through light behavior. Interference and diffraction of light prove that it can behave as a wave while other aspects, such as the photoelectric effect of light treat it as it is made up of particles. This phenomenon defined wave-particle duality. It is not just confined to light but other objects as well. From a football to an electron, everything can be considered to be exhibiting wave-particle duality. Although, the particle nature dominates when the objects are relatively large and in the case of small objects, both particle and wave-like behavior are exhibited by the object. For example, an electron has been observed to exhibit a similar interference pattern as light when they are incident on a double slit. 

Theories of Wave – Particle Duality

In physics and chemistry, the light and matter hold wave and particle-like characteristics. The phenomena of wave-particle duality received a lot of attention by physicists early in this century. Waves behaved like a particle, particles could behave like waves. This duality led to many theories behind the phenomena. Some of these theories are still followed in the science of modern physics.

The De Broglie Wavelength

In 1923, Louis de Broglie suggested the duality of wave-particles can be applicable to matter as well. de Broglie’s prediction of wave properties of a particle was proven true when beams of electrons and neutrons were directed at a crystal and diffraction patterns were observed. He further proposes that any particle of matter that has momentum (p) also has an associated wavelength (λ):

λ = h/p.

The same equation also applies to a photon. He further states that the wave properties of matter are observable for small objects. Moreover, the theory of photoelectric effect by Albert Einstein further contributed to De Broglie’s Theory and substantiated it with the proof that particles and waves could overlap. 

Newton’s Corpuscular Theory

As per this theory, Newton defines light to be made up of corpuscles. These corpuscles of light travel in a straight line. The law of reflection justifies the wave-like nature of light when it bounces off a planar surface on reflection. But in the case of refraction, it has been stated that light travels more slowly in dense material, which justifies the particle-nature of light. 

Huygens Wave Theory

This theory was written by Huygens in 1678. The theory proposed a principle that each point of a light waveform could be considered to be the source of a spherical wave. The Huygens Wave This principle has greatly assisted the development of the wave theory of light by other physicists such as Fresnel and Kirchhoff. 

Quantum View of Light

Light exhibiting particle properties on the quantum scale of atoms has been proven by the photoelectric effect. This theory implies that there must be a particle treatment of refraction of light by achieving a sufficient localization of energy to eject an electron from a surface. However, for optic, the wave view of the light is generally the approach that is adopted.

 

Wrap up on Wave – Particle Duality

The wave-particle duality has been under research for years. Several physicists have drawn their individual theories that link up and summarise and prove the existence of wave-particle duality of matter. Moreover, it has been observed that the larger the amplitude of the wave, the larger the probability of finding a particle, i.e., electron there. The opposite of this has also been observed, where the probability of finding an electron is smaller when the amplitude of the wave is smaller. Such is the nature and characteristics of matter. Furthermore, when the electrons are emitted, there is also a release of kinetic energy. The greater the intensity, the higher the energy releases. This relation brings another complexity to wave-particle duality as the energy of the wave is directly proportional to its amplitude, it leaves scientists to explore high-intensity lights that did not affect the overall kinetic energy.