CBSE Class 11-science Answered
Isothermal process : Since temperature remains constant in an isothermal process, dU = 0
From the first law of thermodynamics, dQ = dU + dW
Therefore, dQ = dW = PdV
(a) Therefore, if a gas is to expand isothermally, then an amount of heat equivalent to the work done by the gas will have to be supplied to it from the external source.
(b) During isothermal compression, dV will be negative. This implies that during an isothermal compression, the amount of heat equivalent to the work done on the gas will have to be removed from it.
(c) During isothermal compression or expansion, there is no change in the internal energy of the gas.