BHU PMT BHU PMT Solved Paper-2004

  • question_answer
    In the relation \[y=a\,\,\cos \left( \omega t-kx \right)\],the dimensional formula for k is :                             [BHU PMT-2004]

    A)  \[\left[ {{M}^{0}}{{L}^{-1}}{{T}^{-1}} \right]\]                    

    B)  \[\left[ {{M}^{0}}L{{T}^{-1}} \right]\]

    C)  \[\left[ {{M}^{0}}{{L}^{-1}}{{T}^{0}} \right]\]                      

    D)  \[\left[ {{M}^{0}}LT \right]\]

    Correct Answer: C

    Solution :

                     Key Idea: Every equation relating physical quantities should be in dimensional balance. The given equation is in dimensional balance, hence the dimensions of the terms on both sides of the equation must be the same.                 \[\therefore \]                  \[y=a\,\cos \left( \omega t-kx \right)\] \[y\] has dimensions of length and a that is amplitude also has dimensions of length, hence \[\left( \omega t-kx \right)\] should be dimensions, that is                                                 \[\left[ k \right]=\frac{1}{\left[ x \right]}=\frac{1}{\left[ L \right]}\] Dimensions of \[k=\left[ {{M}^{0}}{{L}^{-1}}{{T}^{0}} \right]\]


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