JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2014

  • question_answer
    A Carnot engine has efficiency 1/5. Efficiency becomes 1/3 when temperature of sink is decreased by 50 K. What is the temperature of sink?

    A) 325 K     

    B) 375 K   

    C) 300 K    

    D) 380 K

    Correct Answer: C

    Solution :

                    \[\Delta APQ,\] \[\tan {{30}^{o}}=\frac{PQ}{AP}\Rightarrow \frac{1}{\sqrt{3}}=\frac{100}{AP}\] \[=1-\frac{{{Q}_{L}}}{{{Q}_{H}}}\] Also we can show that \[AP=100\sqrt{3}\] \[\Delta BPQ,\]                                              ...(i) \[\tan {{60}^{o}}=\frac{PQ}{PB}\Rightarrow \sqrt{3}=\frac{100}{PB}\] and      \[\Rightarrow \]                           ...(ii) From Eq.(i) \[PB=\frac{100}{\sqrt{3}}\] \[AP+PB=100\left( \sqrt{3}+\frac{1}{\sqrt{3}} \right)\Rightarrow AB=\frac{400}{\sqrt{3}}m\] Substituting the value of \[{{\tan }^{-1}}x\] in Eq.(ii), we get \[{{\cot }^{-1}}x\] \[x\in R\] \[{{\cos }^{-1}}(2-x)\] \[-\text{1}\le \text{2}-x\le \text{1}\] \[\therefore \]


You need to login to perform this action.
You will be redirected in 3 sec spinner