Dual Nature Of Light Question 152

Question: A proton and an a-particle are accelerated through a potential difference of 100 V. The ratio of the wavelength associated with the proton to that associated with an a-particle is [DCE 2002; DPMT 2003]

Options:

A) $ \sqrt{2}:1 $

B) $ 2:1 $

C) $ 2\sqrt{2}:1 $

D) $ \frac{1}{2\sqrt{2}}:1 $

Show Answer

Answer:

Correct Answer: C

Solution:

$ \lambda =\frac{h}{\sqrt{2mQV}}\Rightarrow \lambda \propto \frac{1}{\sqrt{mQ}} $
$ \Rightarrow \frac{{\lambda_{p}}}{{\lambda_{\alpha }}}=\sqrt{\frac{{m_{\alpha }}{Q_{\alpha }}}{m_{p}Q_{p}}} $ $ =\sqrt{\frac{4m_{p}\times 2Q_{p}}{m_{p}\times Q_{p}}}=2\sqrt{2} $