NEET Sample Paper NEET Sample Test Paper-87

  • question_answer
    A sonometer wire supports a 4 kg load and vibrates in fundamental mode with a tuning fork of frequency 416 Hz. The length of the wire between the bridges is now doubled. In order to maintain fundamental mode, the load should be changed to

    A) 1 kg                 

    B)        2 kg

    C) 4 kg                 

    D)        16 kg

    Correct Answer: D

    Solution :

    [d] Load supported by sonometer wire = 4 kg Tension in sonometer wire = 4 g If \[\mu =\] mass per unit length then frequency' \[\upsilon =\frac{1}{2l}\sqrt{\frac{T}{\mu }}\] \[\Rightarrow \]\[416=\frac{1}{2l}\sqrt{\frac{4g}{\mu }}\] When length is doubled, i.e.,\[l'=2l\] Let new load =L As, \[\upsilon '=\upsilon \] \[\therefore \]\[\frac{1}{2l'}\sqrt{\frac{Lg}{\mu }}=\frac{1}{2l}\sqrt{\frac{4g}{\mu }}\] \[\Rightarrow \]\[\frac{1}{4l'}\sqrt{\frac{Lg}{\mu }}=\frac{1}{2l}\sqrt{\frac{4g}{\mu }}\] \[\Rightarrow \]\[\sqrt{L}=2\times 2\]\[\Rightarrow \]\[L=16\,kg\]


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