A microscopic variable is a variable pertaining to the individual atoms and molecules, making up the system. Examples include:
- Component of a particle’s velocity
- The orientation of the axis of a diatomic molecule
- The quantum number for a particular vibrational mode of a molecule
- The magnetic moment vector of a paramagneticion
For a monatomic gas molecule, the speed of the molecule is a microscopic variable. For a magnetic material, the angle between the molecular or atomic magnetic moment and magnetic field is a microscopic variable. In the case of a ‘’real gas’’, the separation of the molecules is also a microscopic variable.
Macroscopic Variable can be described as a measurable quantity used to describethe gross state of the system. It depends collectively on the behavior of all the atoms and molecules. Macroscopic variables can also be referred to as thermodynamic variables.