Question

Which formula may be used for the momentum of all particles, with or without mass?

Short answer

De-Broglie’s formula could be used for mass and mass-less particles:

\[{\rm{p = }}\frac{{\rm{h}}}{{\rm{\lambda }}}\]

Step-by-step solution

Formula to describe the momentum of particles

As per De-Broglie's hypothesis which is all microscopic particles, whether mass-less, like photons or having mass, like electrons, have wave properties. Where the relationship between momentum and wavelength is fundamental for all particles. So, we can use this formula to describe the momentum of all particles with or without mass:

\[p = \frac{h}{\lambda }\]

De- Broglie’s formula

Where, \[{\rm{p}}\]is the momentum, \[{\rm{h}}\] is Planck's constant and \[{\rm{\lambda }}\] is the wavelength.

Therefore, De-Broglie’s formula could be used for mass and mass-less particles:

\[{\rm{p = }}\frac{{\rm{h}}}{{\rm{\lambda }}}\]