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KVPY Sample Paper KVPY Stream-SX Model Paper-26

  • question_answer
    A chord attached about an end to a vibrating fork 'divides it into 6 loops, when its tension is 36 N. The tension at which it will vibrate in 4 loops is -

    A) 24 N

    B) 36 N

    C) 64 N

    D) 81 N

    Correct Answer: D

    Solution :

    For waves along a string: \[v\,\,\alpha \,\,\sqrt{T}\] \[\Rightarrow \,\,\,\,\lambda \,\alpha \,\sqrt{T}\]Now for 6 loops: \[3{{\lambda }_{1}}=L\]\[\Rightarrow {{\lambda }_{1}}=L/3\] & for 4 loops \[2{{\lambda }_{2}}=L\]\[\Rightarrow {{\lambda }_{2}}=L/2\]\[\Rightarrow \frac{{{\lambda }_{1}}}{{{\lambda }_{2}}}=\frac{2}{3}\]\[\Rightarrow {{T}_{2}}=\frac{9}{4}\times {{T}_{1}}=\frac{9}{4}\times 36\]\[=81\,\,N.\]


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