JEE Main & Advanced Physics Thermodynamical Processes Sample Paper Topic Test - Thermodynamical Processes

  • question_answer
    2 moles of a mono-atomic gas undergo isobaric expansion as shown in figure. The efficiency for the process is found to be \[\frac{x}{10}\]. Find the value of\[x\].

    A) 2

    B) 3

    C) 4

    D) 5

    Correct Answer: C

    Solution :

    [c] Work done by gas
    \[={{P}_{0}}(2{{V}_{0}}-{{V}_{0}})={{P}_{0}}{{V}_{0}}\]          ...(i)
    Heat input to the gas
    = Work done + Change in internal energy
    \[={{P}_{0}}{{V}_{0}}+\frac{f}{2}nR\Delta T\]
    \[={{P}_{0}}{{V}_{0}}+\frac{3}{2}(nR{{T}_{f}}-nR{{T}_{i}})\]
    \[={{P}_{0}}{{V}_{0}}+\frac{3}{2}(2{{P}_{0}}{{V}_{0}}-{{P}_{0}}{{V}_{0}})\]
    \[\therefore \]    Heat input \[=\frac{5}{2}{{P}_{0}}{{V}_{0}}\]   ....(ii)
    Efficiency \[=\frac{\text{Work}\,\text{done}}{\text{Heat}\,\text{inpup}}\]
    \[=\frac{{{P}_{0}}{{V}_{0}}}{\frac{5}{2}{{P}_{0}}{{V}_{0}}}=\frac{2}{5}\]
    Efficiency \[=\frac{4}{10}=\frac{x}{10}\Rightarrow \,x=4\]


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