Question

Assertion: Work done by a gas in isothermal expansion is more than the work done by the gas in the same expansion, adiabatically. Reason: Temperature remains constant in isothermal expansion and not in adiabatic expansion

Carnot engine is a reversible engine operating between two temperatures T1 (source) and T2 (sink). The Carnot cycle consists of two isothermal processes connected by two adiabatic processes. The efficiency of a Carnot engine is given by η = 1 - T2/T1

For an ideal gas, the equation of state is the ideal gas relation PV = µRT. For a fixed amount of the gas i.e. given µ, there are thus, only two independent variables, say P and V or T and V. The pressure-volume curve for a fixed temperature is called an isotherm. The thermodynamic state variables are of two kinds: extensive and intensive. Extensive variables indicate the 'size' of the system. Intensive variables such as pressure and temperature do not. To decide which variable is extensive and which intensive, think of a relevant system in equilibrium, and imagine that it is divided into two equal parts. The variables that remain unchanged for each part are Intensive.

If an engine takes 5J of heat energy from a reservoir and rejects 3J to the surroundings, what is its efficiency?