In this process, P and V change but T = constant i.e., change in temperature ∆T = 0.
Condition for isothermal process :
(i) The walls of the container must be perfectly conducting.
(ii) The speed of process should be very slow.
Equation of state : In all isothermal process Boyle’s law is obeyed. Hence equation of state is PV = constant.
Example of isothermal process :
(i) Melting process [Ice melts at constant temperature 0ºC]
(ii) Boiling process [water boils at constant temperature 100ºC]
Indicator diagram
Work done W
Heat supplied in isothermal process : ∆Q = ∆W i.e., heat supplied is used to do work against external surrounding.
