J & K CET Medical J & K - CET Medical Solved Paper-2003

  • question_answer
    Two wires made up of the same material are of equal length but their radii are in the ratio of 1:2. On stretching each of these two strings by fundamental frequencies is :

    A)  1 : 4                                      

    B)  4 : 1

    C)  2 : 1                                      

    D)  1 : 2

    Correct Answer: C

    Solution :

                    The fundamental frequency of a wire is given by \[n=\frac{1}{2l}\sqrt{\frac{T}{m}}\] where\[l\]is length of wire, T the tension and m the mass per unit length. \[m=\frac{mass\text{ }of\text{ }wire}{length\text{ }of\text{ }wire}\] \[=\frac{\pi {{r}^{2}}L\times density}{L}=\pi {{r}^{2}}d\] \[n=\frac{1}{2l}\sqrt{\frac{T}{\pi {{r}^{2}}d}}\] \[\Rightarrow \]               \[n=\frac{1}{2rl}\sqrt{\frac{T}{\pi d}}\] \[\therefore \]  \[\frac{{{n}_{1}}}{{{n}_{2}}}=\frac{{{r}_{2}}}{{{r}_{1}}}=\frac{2}{1}\]


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