NEET Physics Photo Electric Effect, X- Rays & Matter Waves NEET PYQ-Photo Electric Effect,X-Rays

  • question_answer
    If the momentum of an electron is changed by p, then the de-Broglie wavelength associated with it changes by 0.5%. The initial momentum of electron will be                                                                     [AIPMT (M) 2012]

    A)  200 p  

    B)       400 p

    C)  \[\frac{p}{200}\]          

    D)       100 p

    Correct Answer: A

    Solution :

    de-Broglie wavelength \[\lambda =\frac{h}{p}\]
    Here      \[\left| \frac{\Delta \lambda }{\lambda } \right|=\left| \frac{\Delta p}{p} \right|\]
    \[\frac{0.5}{100}=\frac{p}{{{p}_{i}}}\]
    \[{{p}_{i}}=\frac{100}{0.5}p\]
    \[{{p}_{i}}=200p\]


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