NEET Solved Paper 2016 Question 20
Question: An electron of mass m and a photon have same energy E. The ratio of de-Broglie wavelengths associated with them is :
Options:
A) $ \frac{1}{c}{{( \frac{E}{2m} )}^{\frac{1}{2}}} $
B) $ {{( \frac{E}{2m} )}^{\frac{1}{2}}} $
C) $ c{{( 2mE )}^{\frac{1}{2}}} $
D) $ \frac{1}{xc}{{( \frac{2m}{E} )}^{\frac{1}{2}}} $ (being velocity of light)
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Answer:
Correct Answer: A
Solution:
- For electron $ ,{\lambda_e}=\frac{h}{\sqrt{2mE}} $ For Photon $ E=pc $
$ \Rightarrow $ $ {\lambda _{Ph}}=\frac{hc}{E} $
$ \Rightarrow $ $ \frac{{\lambda_e}}{{\lambda _{Ph}}}=\frac{h}{\sqrt{2mE}}\times \frac{E}{hc}={{( \frac{E}{2m} )}^{1/2}}\frac{1}{c} $
