Q11 of 27 Page 85

Consider a heat engine as shown in Fig. 12.7. Q1 and Q2 are heat added to heat bath T1 and heat taken from T2 in one cycle of engine. W is the mechanical work done on the engine. If W > 0, then possibilities are:


From the above diagram, we get that

it is given that W>0


∴


Thus, there arises two cases –


(a) when both are positive


⇒


(b) when both are negative


⇒


option (a, c) is correct.

More from this chapter

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9

Figure 12.5 shows the P-V diagram of an ideal gas undergoing a change of state from A to B. Four different parts I, II, III and IV as shown in the figure may lead to the same change of state.


 10

Consider a cycle followed by an engine (Fig. 12.6) 1 to 2 is isothermal 2 to 3 is adiabatic 3 to 1 is adiabatic Such a process does not exist because


 12

Can a system be heated and its temperature remains constant?

 13

A system goes from P to Q by two different paths in the P-V diagram as shown in Fig. 12.8. Heat given to the system in path 1 is 1000 J. The work done by the system along path 1 is more than path 2 by 100 J. What is the heat exchanged by the system in path 2?