Do Photons Have Mass? Physics Forums FAQ

[Suraj Nehra]

I read the FAQ about photons not having mass: https://www.physicsforums.com/threads/do-photons-have-mass.511175/

But De-Broglie's equation says that wavelength=Plank constant / mass x velocity
i.e.
λ=h/mv

inserting values in the above relation we find the mass of a photon having certain wavelength

 

[ChrisVer]

But De-Borgle's equation says that wavelength=Plank constant / mass x velocity
i.e.
λ=h/mv

inserting values in the above relation we find the mass of a photon having certain wavelength

You wrote the debroglie equation for a massive particle (where you can write its momentum as p=mv which is not correct for the photon). You should use instead $\lambda= \frac{h}{p}$.