Which of the following processes is known as a constant entropy process?

CONCEPT:

• Adiabatic process: When a thermodynamic system undergoes a change in such a way that no exchange of heat takes place between Systems and surroundings, the process is known as an adiabatic process.
• ΔQ = 0

Entropy (S): It is a measure of the disorder of the molecular motion of a system.

• Greater is the disorder, greater is the entropy.
• The change in entropy is,

\(⇒ {\rm{\Delta }}S = \frac{{{\rm{\Delta }}Q}}{T}\)

Where ΔQ = Heat exchange, T = temperature of the system

EXPLANATION:

• According to the first law of Thermodynamics:

⇒ ΔQ = ΔW + ΔU

Now for an adiabatic process ΔQ = 0.

i.e. 0 = ΔU + ΔW

⇒ ΔW = - ΔU = U1 - U2

• From the above, it is clear that the entropy of a system depends upon the heat exchange and temperature of the system.
• Since the system is adiabatic (ΔQ = 0) so, entropy is zero. Therefore entropy remains constant.