CHEMISTRY COMMUNITY

Why cant the De Broglie's equation be used for light?

De Broglie's equation requires an object to have a mass, therefore, the equation cannot be used for light because light does not have a mass.

The photons have no mass. Keep in mind that there is a similar situation in which we cannot apply equations for electromagnetic radiation to electrons. For example, we cannot use c = lambda nu for problems involving properties of electrons.

De Broglie's equation is used for objects that has mass and behaves similarly to a wave. It also require momentum or velocity. Light theoretically doesn't have mass so the equation can't be used.

No, light cannot be used.

The equation requires an object that has mass, but light does not have that. Thus, light cannot be used in this equation.

While all the previous replies have stated that light doesn't have mass and I agree, I just wanted to add that I remember Dr. Lavelle saying that the equation can only be used for particles with rest mass (mass at rest). It can be applied to everything else but light.

Light does not have mass, which is a required variable in the De Broglie equation.

De Broglie used light in order to derive the equation. The equation will work for any particle with momentum and it has a wavelength with its properties.

De Broglie suggested that the equation works for any particle with momentum, that has a rest mass, and has wavelike properties.

What is the difference between λ=h/p and c= λ*ν

The first equation you've listed is the De Broglie equation and that's used for electrons or objects that have a mass. You cannot use light with the De Broglie equation. The second equation you CAN use for photons (light).

De Broglie's equation requires an object to have a mass
wavelength = h/mv

since wavelength=h/mv, the object must have a mass. While Light has a velocity, it does not have a mass to calculate

A photon does not have mass which is required for the de Broglie's equation where

You need to have mass to use the De Broglie Equation, however photons of light do not have mass.

Photons don't have mass so the equation isn't applicable for it.

Photons do not have mass, only momentum.