Question

A proton and an electron have same kinetic. Which one has greater de-Broglie wavelength and why?

Answer 1

Since de-Broglie wavelength λ in terms of kinetic energy is given as

`lambda = h/(sqrt(2mE_k))`

Where Ek is kinetic energy, m is mass of electron and h is the Planck’s constant.

Thus for electron and proton with same kinetic energy, de Broglie wavelength would depend on mass.

Since `lambda ∝= 1/sqrtm`

Now mp > me so, λe>λp.

Hence wavelength of electron is greater than wavelength of proto