Question

Consider a heat engine as shown in figure 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

(i) Q1 > Q2 > 0 (ii) Q2 > Q1 > 0

(iii) Q2 < Q1 < 0 (iv) Q1 < 0, Q2 > 0

• A. (i) and (ii)
• B. (i) and (iii)
• C. (ii) and (iii)
• D. (ii) and (iv)

Answer 1

Answer: (B)

(i) and (iii)

Answer 2

Here the given figure represent the working of a refrigerator $\mathrm { Q } _ { 1 } = \mathrm { Q } _ { 2 } + \mathrm { W }$

If then

If is negative is also negative (but less negative as W > 0)

$\therefore \mathrm { Q } _ { 2 } < \mathrm { Q } _ { 1 } < 0$

Hence (iii) is also correct.