Figure 17.5 shows the P - V diagram for a fixed mass of an ideal gas undergoing cyclic process ABCA.AB represents isothermal process. Which of the graphs shown in Fig. 17.6 represents the P - T diagram of the cyclic process ?
Curve AB represents isothermal change in which the pressure decreases from 2P to P and volume increases from V to 2V, the temperature remaining constant. Since the temperature remains constant between A and B, the P - T graph should be perpendicular to T - axis between A and B. Hence graph (d) is obviously wrong. Diagrams (a) and (b) are also incorrect, because according to these graphs, the pressure remains constant between A and B. But the pressure reduces from 2P to P between A and B. Hence the only correct choice is diagram (c).