B.Sc. Sem-III Phy-I Unit-II (Concept of Thermodynamics)

1. Shri Govindrao Munghate Arts and Science
College , Kurkheda
Department of Physics
Topic –Work done During an Adiabatic Process
Prof. B.V. Tupte
Head, Department of Physics
Shri Govindrao Munghate Arts and Science College Kurkheda.

2. The system does not exchange heat with the surrounding
 System is thermally insulated from the surrounding
Adiabatic Process
• An adiabatic process transfers no heat
ΔU = Q – W
– But Q = 0 , → ΔU = – W
When a system expands adiabatically, W is positive (the systemdoes work) so
ΔU is negative.
When a system compresses adiabatically, W is negative (work is done on the system) so
ΔU is positive.
Adiabatic processes can occur when the system is well insulated or a very rapid
process occurs so that there is not enough time for a significant heat to be
transferred (e.g., rapid expansion of a gas; a series of compressions and expansions
as a sound wave propagates through air).

3. System is thermally insulated from the surrounding. The gas expand from
volume V1 to V2 as shown by indicator diagram. The Work done by the gas
for an increase in volume dV is PdV

5. Hence the work done in adiabatic process depends only
upon the initial and final temperature T1 and T2 . Thus the
work done along any adiabatic between two isothermals is
independent of the particular adiabatic.