Question

A proton and an electron have same kinetic energy. Which one has greater de Broglie wavelength. Justify.

Answer 1

de-Broglie wavelength of the particle is λ = \(\frac{h}{p}\) = \(\frac{h}{\sqrt{2mK}}\)

i.e. λ ∝\(\frac{h}{\sqrt m}\)

As m_e << m_p so λ_e >> λ_P 

Hence protons have greater de-Broglie wavelength.