Physics is the study of the basic principles that govern the physical world around us.

The major branches of the physics are Classical, Relativistic and Quantum.

Classical physics deals with the classical mechanics, electromagnetism, thermodynamics and statistical mechanics.

Relativistic deals with the relativity theory.

Quantum physics deals with the quantum mechanics, quantum electrodynamics, quantum field theory and quantum statistics.

Now, we are interested to discuss the quantum mechanics.

Letâ€™s discuss the quantum mechanics.

Quantum mechanics is the part of physics which describes the smallest things are in the universe, Like molecules, atoms, etc.

Hence, the quantum mechanics is the branch of physics relating to the very small.

Suppose, we have a cheque of one lac and we submit that cheque in the bank. Then bank will give the same amount back.

But, when we have a cheque of one lakh and $15.50$ paisa then the bank will not give anything because paisa is smallest defined quantity.

So, it cannot be in the form of fraction of paisa. Because it is not defined in indian currency.

There are many quantities which exist in certain minimum or elementary amount or integer multiple of these elementary amount like currency.

These quantities are set to be quantized and the minimum amount is called Quantum.

Now, a quantum of light wave of frequency (f) having energy (E) is given by,

Further, we will simplify it as,

After putting the value of frequency, energy will be as,

Hence, in quantum mechanics, we deal with the things which exist in certain minimum or elementary amount or the integer multiple of that minimum amount.

Revision

Quantum mechanics is the part of physics which describes the smallest things in the universe, Like molecules, atoms, etc.

A quantum of light wave of frequency (f) having energy (E) is given by,