JEE Main & Advanced JEE Main Paper (Held on 12-4-2019 Afternoon)

  • question_answer
    A Carnot engine has an efficiency of 1/6. When the temperature of the sink is reduced by \[62{}^\text{o}C\], its efficiency is doubled. The temperatures of the source and the sink are, respectively [JEE Main 12-4-2019 Afternoon]

    A) \[124{}^\text{o}C,62{}^\text{o}C\]          

    B) \[37{}^\text{o}C,99{}^\text{o}C\]

    C) \[62{}^\text{o}C,124{}^\text{o}C\]          

    D) \[99{}^\text{o}C,37{}^\text{o}C\]

    Correct Answer: B

    Solution :

    Efficiency of Carnot engine \[=1-\frac{{{T}_{\sin k}}}{{{T}_{source}}}\] Given, \[\frac{1}{6}=1-\frac{{{T}_{\sin k}}}{{{T}_{source}}}\Rightarrow \frac{{{T}_{\sin k}}}{{{T}_{source}}}=\frac{5}{6}\]                  .....(1) Also, \[\frac{2}{6}=1-\frac{{{T}_{\sin k}}-62}{{{T}_{source}}}\Rightarrow \frac{62}{{{T}_{source}}}=\frac{1}{6}\]           ?..(2) \[\therefore \]\[{{T}_{source}}=372K={{99}^{o}}C\] Also, \[{{T}_{\operatorname{sink}}}=\frac{5}{6}\times 372=310K={{37}^{o}}C\] (Note :- Temperature of source is more than temperature of sink)


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