question_answer 21)

                  Consider a heat engine as shown in fig. \[{{Q}_{1}}\] and \[{{Q}_{2}}\] are heat added to heat both \[{{T}_{1}}\] and heat taken from \[{{T}_{2}}\] in one cycle of engine. W is the mechanical work done on the engine. If \[W>0,\]then possibilities are : (a) \[{{Q}_{1}}>{{Q}_{2}}>0\]                (b) \[{{Q}_{2}}>{{Q}_{1}}>0\] (c) \[{{Q}_{2}}<{{Q}_{1}}<0\]                 (d) \[{{Q}_{1}}<0,\,\,{{Q}_{2}}>0\]                

Answer:

                  (a, c) According to law of conservation of energy,             \[W+{{Q}_{2}}={{Q}_{1}}\] or \[{{Q}_{2}}={{Q}_{1}}W\]