JEE Main & Advanced Sample Paper JEE Main Sample Paper-28

  • question_answer
    The two particles A and B have de-Broglie wavelength 1 nm and 5 nm respectively. If mass of A is four times the mass of B, then the ratio of kinetic energies of A and B would be

    A)  \[5:1\]                                 

    B)  \[25:4\]

    C)  \[20:1\]                              

    D)  \[5:4\]

    Correct Answer: B

    Solution :

    \[K.E.=\frac{1}{2}m{{v}^{2}}=\frac{{{(P)}^{2}}}{2m}\]                      \[P=\frac{h}{\lambda }\] \[K.E.=\frac{h}{2m{{\lambda }^{2}}}\] \[\therefore \frac{{{(K.E.)}_{A}}}{{{(K.E.)}_{B}}}=\frac{{{m}_{B}}\lambda _{B}^{2}}{{{m}_{A}}\lambda _{A}^{2}}=\frac{{{m}_{B}}}{4{{m}_{B}}}.\frac{{{(5)}^{2}}}{{{(1)}^{2}}}=\frac{25}{4}\]


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