# Quantum Physics

We will study about Quantum Physics and Classical physics, Newton’s laws of motion can explain the behaviour of macroscopic objects or objects that are at a scale of human interaction and experience, even including astronomical objects. But classical physics isn’t able to explain the behaviour of macroscopic objects or objects that are at a scale of an atom.

### Dual Behaviour of Matter:

This is mainly because the behaviour of macroscopic objects is practically particle in nature, they do have wave nature but it is negligible because of their huge masses; whereas on the other hand the atomic level particles have very little mass and hence both particle and wave nature is prevalent in them. This dual behaviour of displaying both particle and wave nature is known as dual behaviour of matter and for every particle, the particle nature comes from its mass and the wave nature comes from its matter-wave defined by De-Broglie relationship which is given by,

λ = $\frac {h}{mv}$

Where,

λ = wavelength of the matter

h = plank’s constant

m = mass of the matter

v = velocity of matter

Classical Physics hasn’t been able to explain the dual behaviour of a matter and Heisenberg’s uncertainty principle, according to which the position and momentum of a sub-atomic particle can be calculated simultaneously with some degree of inaccuracy. Hence, there was a need for a new theory that could explain the behaviour of atomic and sub-atomic particles.

So, this led to the birth of quantum physics – It is a branch of science that explains the physical phenomenon by microscopic and atomic approach and takes into account the dual behaviour of matter. It is theoretical physics and it specifies the laws of motion that the microscopic objects obey. When quantum mechanics is applied to macroscopic objects (for which wave-like properties are insignificant) the results are the same as those from classical mechanics.

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