JEE Main & Advanced Physics Wave Mechanics Question Bank Critical Thinking

  • question_answer
    In Melde's experiment, the string vibrates in 4 loops when a 50 gram weight is placed in the pan of weight 15 gram. To make the string to vibrates in 6 loops the weight that has to be removed from the pan is [MH CET 2004]

    A)            0.0007 kg wt                         

    B)            0.0021 kg wt

    C)            0.036 kg wt                           

    D)            0.0029 kg wt

    Correct Answer: C

    Solution :

               Frequency of vibration of string is given by \[n=\frac{p}{2l}\sqrt{\frac{T}{m}}\]Þ \[p\sqrt{T}=\]constant Þ \[\frac{{{p}_{1}}}{{{p}_{2}}}=\sqrt{\frac{{{T}_{2}}}{{{T}_{1}}}}\] Hence\[\frac{4}{6}=\sqrt{\frac{{{T}_{2}}}{(50+15)gm\text{-}force}}\]Þ \[{{T}_{2}}=28.8\,gm\text{-}f\] Hence weight removed from the pan \[={{T}_{1}}-{{T}_{2}}=65-28.8=3.62\]gm-force = 0.036 kg-f.


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