JEE Main & Advanced Physics Wave Mechanics Question Bank Vibration of String

  • question_answer
    If the length of a stretched string is shortened by 40% and the tension is increased by 44%, then the ratio of the final and initial fundamental frequencies is [EAMCET 2003]

    A)            2 : 1                                          

    B)            3 : 2

    C)            3 : 4                                          

    D)            1 : 3

    Correct Answer: A

    Solution :

                         Fundamental frequency in case of string is                    \[n=\frac{1}{2l}\sqrt{\frac{T}{m}}\Rightarrow n\propto \frac{\sqrt{T}}{l}\Rightarrow \frac{n'}{n}=\sqrt{\frac{T'}{T}}\times \frac{l}{l'}\]                    putting \[T'=T+0.44T=\frac{144}{100}T\] and \[l'=l-0.4l=\frac{3}{5}l\]                    We get \[\frac{n'}{n}=\frac{2}{1}\].


You need to login to perform this action.
You will be redirected in 3 sec spinner