Dual nature of matter and light

Albert Einstein, a German scientist, in 1905 developed a theory stating that light has a dual nature. He proposed that light can exist as a wave or a particle. The dual nature of matter has led to:


A .de Broglie wave

According to Louis de Broglie, both macroscopic and microscopic substances are dual. The wave that is associated with such particles is referred to as a matter-wave. We can calculate the wavelength of such waves using the equation  E=hv. Where h is the planks constant, the frequency of the wave and E is the energy. Photons that contain particle character lead to the following relationship:


E= mc   where m is the mass of the photon and c is the velocity of light.

Here, we need to recall that:

hv= m0c2

but c=v          v=

replacing in hv= m0c2   gives

h= m0c2

Making h as the subject of the formula

h= m0c2

Hence wavelength, λ=h/(m0c2 )


The equation illustrated above is what is called the de Broglie equation, and is the de Broglie wavelength. It should be noted that the momentum of a particle is inversely proportioned to the de Broglie wavelength.






 De-Broglie relationship

Generally, the de- Broglie relationship doesn't have importance in our day-to-day life. For this reason, it is not easy for us to observe/adhere to any nature that is related to the motion of any running object.


Heisenberg’s uncertainty principle

Heisenberg's uncertainty principle states that it is impossible to determine the exact position and momentum of an electron simultaneously.


It is true that once the position of the electron is known, its velocity will be uncertain. Conversely, if we know the velocity of an electron, then its position will be uncertain. Heisenberg's principle rules out the existence of absolute paths of electrons and other related articles.


Plank’s Quantum Theory

This theory states that when a black body is heated, it emits thermal radiations having different wavelengths or frequencies. In order to prove this theory, Max Planck put forward his quantum theory. The main points of quantum theory are, substances radiate or absorb energy intermittently in the form of small packets or bundles of energy.  The smallest packet of energy is called the quantum. The energy of a quantum is directly proportional to the frequency of the radiation that was emitted, which is written as  E µ n (or) E = hn where n is the frequency of radiation and h is Planck’s constant having the value 6.626 X 10–27 erg – sec or 6.626 X 10–34 J–sec.  A body can radiate or absorb energy in whole-number multiples of a quantum hn, 2hn,3hn………..nhn. Where ‘n' is the positive integer.  Niels Bohr used this theory to explain the structure of the atom.




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