Nov. 4, 2019

First Law of Thermodynamics (FLOT):

First Law of Thermodynamics (FLOT)

(1) It is a statement of conservation of energy in thermodynamical process.

(2) According to it heat given to a system (∆Q) is equal to the sum of increase in its internal energy (∆U) and the work done (∆W) by the system against the surroundings.

∆Q = ∆U + ∆W

When a thermodynamic system undergoes a physical change in such a way that its pressure remains constant, then the change is known as isobaric process.


(1) Equation of state : In this process V and T changes but P remains constant. Hence Charle’s law is obeyed in this process

Hence if pressure remains constant

V ∝ T → V1/T1 = V2/T2

(2) Indicator diagram : Graph 1 represents isobaric compression.