MGIMS WARDHA MGIMS WARDHA Solved Paper-2007

  • question_answer
    If the vibrations of a string are to be increased by a factor of two, the tension in the string should be made

    A) twice                                    

    B) four times

    C) eight rimes                        

    D) half

    Correct Answer: B

    Solution :

    The frequency of vibration of a string is given by \[n=\frac{1}{2l}\sqrt{\frac{T}{m}}\]where \[l\]is length, T the tension and m the mass per unit length. Given,     \[{{n}_{1}}=n,{{n}_{2}}=2n\] \[\therefore \]  \[\frac{{{n}_{1}}}{{{n}_{2}}}=\frac{n}{2n}=\sqrt{\frac{{{T}_{1}}}{{{T}_{2}}}}\] \[\Rightarrow \]               \[\frac{1}{4}=\frac{{{T}_{1}}}{{{T}_{2}}}\] \[\Rightarrow \]               \[{{T}_{2}}=4{{T}_{1}}\] Hence, to increase n by a factor of 2 tension must increase four times.


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