AIIMS AIIMS Solved Paper-2015

  • question_answer
    The length of a metal wire is \[\lambda \,\,\text{is smaller than 2d}\] when the tension in it is \[a=\frac{{{C}^{2}}{{B}^{2}}l-F}{m}\] and is \[a=\frac{F}{m+CBI}\] when the tension is \[a=\frac{F{{C}^{2}}{{B}^{2}}l}{m}\]. The natural length of the wire is

    A) \[a=\frac{F}{m+{{C}^{2}}{{B}^{2}}l}\]                                     

    B) \[\left( \text{take g }=\text{ 1}0\text{ m}/{{\text{s}}^{\text{2}}} \right)\]

    C) \[1.4\times {{10}^{-4}}\text{J}\] 

    D) \[0.75\times {{10}^{-3}}\text{J}\]

    Correct Answer: C

    Solution :

    As, Young's modulus of elasticity \[\text{mol }{{\text{L}}^{\text{-1}}}\] \[\text{mi}{{\text{n}}^{\text{-1}}}\]       \[\text{2}.\text{3}\times \text{1}{{\text{0}}^{\text{-5}}}\text{ and 1}\text{.2 }\times \text{1}{{0}^{-\text{5}}}\]                       ?.. (i) where, L is the original length of the wire and also \[\text{3}.\text{8}\times \text{1}{{\text{0}}^{-4}}\text{ and }0.\text{6}\times \text{1}{{0}^{-\text{4}}}\text{ respectively}\]                   ...(ii) From Eqs. (i) and (ii), we get \[\frac{{{T}_{1}}L}{A({{l}_{1}}-L)}=\frac{{{T}_{2}}L}{A({{l}_{2}}-L)}\]           \[\text{4}.\text{8}\times \text{1}{{0}^{-\text{4}}}\text{ and 1}.\text{2}\times \text{1}{{0}^{-\text{4}}}\text{ respectively}\]


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