The concept of Particle-Wave duality says that every quantum entity (electrons, protons, atoms, molecules etc) has a wave nature and a particle nature. for example, light occurs in two forms. when considering wave nature of light, light occurs in the form of electromagnetic waves, but when considering particle nature of light, light occurs as a stream of particles called photons. This idea emerged after conducting multiple experiments involving quantum particles. There were a few experiments whose reults could only be explained by the particle nature of the quantum particle – for example, the double slit experiment which involved interference, a property of waves – and others could be explained only by the particle nature – for example, the photoelectric effect.
In 1924, Louis De Broglie discovered the wave nature of an electron and he derived a formula to determine the wavelength of this waves. The formula is as follows-
λ = h / mv
Here, λ is the wavelength of the particle, h is the Planck Constant (h = 6.62607015×10−34 J⋅s), m is the mass of the particle and v is the velocity of the particle. It can be implied from the equation above that greater the velocity, shorter the wavelength and smaller the mass, greater the wavelength. An interesting fact is that in addition to quantum particles, everyday macroscopic objects too exhibit wave nature. But the wavelength of such a wave is so small that it is undetectable. This can be seen tested using the equation above. You, my reader can calculate your wavelength by putting the values of your mass and velocity into the equation above and see how unbelievably small the results are.