Question

A proton, an electron and an α particle have the same kinetic energy. Write the de Broglie wavelengths associated with them in increasing order.

Answer 1

We know that de-Broglie's wavelength is given by

`lambda = h/p = h/(mv) = h/(sqrt(2mKE))`

h = Planck's constant,

m = mass of particle

and v = velocity of particle.

If KE is the same, then `lambda prop 1/sqrtm`

The order of mass of electron, proton, and alpha particle is α > p > e⁻, the order of the de-Broglie wavelength is λ_α < λ_P < λ_e−.