J & K CET Medical J & K - CET Medical Solved Paper-2004

  • question_answer
    A particle with rest mass zero is moving with speed c. The de-Broglie wavelength associated with it:

    A)  zero                                     

    B)  infinity

    C) \[\frac{hv}{c}\]                                

    D) \[\frac{{{m}_{0}}c}{h}\]

    Correct Answer: A

    Solution :

                    The de-Broglie wavelength (^) is given by \[\lambda =\frac{h}{p}\]                     ...(i) Where h is Planck's constant, p the momentum. Also,     \[p=mv=\frac{{{m}_{0}}}{\sqrt{1-\frac{{{v}^{2}}}{{{c}^{2}}}}}\]             ... (ii) where\[{{m}_{0}}\]is rest mass, v the velocity and c the speed of light. From Eqs. (i) and (ii), we get                 \[\lambda =\frac{h\sqrt{1-\frac{{{v}^{2}}}{{{c}^{2}}}}}{{{m}_{0}}v}\] Given, \[v=c\] \[\therefore \] \[\lambda =0\]


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