JEE Main & Advanced Physics Kinetic Theory of Gases Question Bank Self Evaluation Test - Kinetic Theory

  • question_answer
    N (< 100) molecules of a gas have velocities 1, 2, 3,........ N km/s respectively. Then ratio of rms speed and average speed is  

    A) 1

    B) \[\frac{\sqrt{\left( 2N+1 \right)\left( N+1 \right)}}{6N}\]

    C) \[\frac{\sqrt{\left( 2N+1 \right)\left( N+1 \right)}}{6}\]

    D) \[2\sqrt{\frac{2N+1}{6\left( N+1 \right)}}\]

    Correct Answer: D

    Solution :

    [d] \[{{V}_{rms}}=\sqrt{\frac{{{1}^{2}}+{{2}^{2}}+....+{{N}^{2}}}{N}}\]  \[=\sqrt{\frac{N\left( N+1 \right)\left( 2N+1 \right)}{6N}}\] \[{{V}_{mean}}=\frac{1+2+....N}{N}=\frac{N\left( N+1 \right)}{2N}\]


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