Question

What is classical domain. I need very basic definition on that.

Answer 1

Classical mechanics deals with the objects which can be observed on a large scale and one can use describe whole system governed by classical laws.

If we talk about a particle who has dimension larger than deBroglie wavelength, then we can use classical mechanics.

If it is smaller than deBroglie wavelength, then the particle shows dual nature. It behave as particle as well as wave.

One can classify the classical domain by knowing the dimensions of the object and comparing it with deBroglie wavelength.