Easy MCQ +4 / -1 PYQ · JEE Mains 2022

An $\alpha$ particle and a carbon 12 atom has same kinetic energy K. The ratio of their de-Broglie wavelengths $({\lambda _\alpha }:{\lambda _{C12}})$ is :

  1. A $1:\sqrt 3$
  2. B $\sqrt 3 :1$ Correct answer
  3. C $3:1$
  4. D $2:\sqrt 3$

Solution

<p>${K_\alpha } = {K_C}$</p> <p>${{p_\alpha ^2} \over {2{m_\alpha }}} = {{p_C^2} \over {2{m_C}}}$</p> <p>${{{p_\alpha }} \over {{p_C}}} = \sqrt {{{{m_\alpha }} \over {{m_C}}}}$</p> <p>So $${{{\lambda _\alpha }} \over {{\lambda _C}}} = {{h/{p_\alpha }} \over {h/{p_C}}} = \sqrt {{{{m_C}} \over {{m_\alpha }}}} $$</p> <p>So ${{{\lambda _\alpha }} \over {{\lambda _C}}} = \sqrt 3$</p>

About this question

Subject: Physics · Chapter: Dual Nature of Matter and Radiation · Topic: Photoelectric Effect

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