JEE Main & Advanced Chemistry Structure of Atom / परमाणु संरचना Question Bank Mock Test - Atomic Structure

  • question_answer
    A photon of frequency n causes photoelectric emission from a surface with threshold frequency \[{{n}_{0}}\].The de Broglie wavelength\[\lambda \]of the photoelectron emitted is given as

    A) \[\Delta n=\frac{h}{2m\lambda }\]         

    B) \[\Delta n=\frac{h}{\lambda }\]

    C) \[\left[ \frac{1}{{{v}_{0}}}-\frac{1}{v} \right]=\frac{m{{c}^{2}}}{h}\]

    D) \[\lambda =\sqrt{\frac{h}{2m\Delta n}}\]

    Correct Answer: D

    Solution :

    [d] \[{{E}_{1}}=IE+KE\]             Or             \[{{E}_{1}}=\]threshold E (or) work function +KE             \[\left( hv=h{{v}_{0}}+\frac{1}{2}m{{u}^{2}} \right)\]             Or             \[hn=h{{n}_{0}}+\frac{1}{2}m{{u}^{2}}\]             \[\frac{1}{2}m{{u}^{2}}=h(n-{{n}_{0}})=h\Delta n\]             \[\left( \lambda =\frac{h}{mu},\therefore u=\frac{h}{m\lambda } \right)\]             Substitute the value of u I equation (i)             \[\frac{1}{2}m.\frac{{{h}^{2}}}{{{m}^{2}}{{\lambda }^{2}}}=h\Delta n\]             \[\frac{h}{2{{\lambda }^{2}}m}=\Delta n\]             \[\therefore \]\[\lambda =\sqrt{\frac{h}{2m\Delta n}}\]


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