Does the Equation E=mc² Apply to Photons?

[Phys_Boi]

If the energy of a photon: E_photon = hν, where h = Planck's constant,
and E = mc², then does hv = mc²

And if so, if c=vλ: E_photon = hc/λ = mc²

Thus mass: m = h/λc ?

 

[Khashishi]

$E=mc^2$ only applies to massive particles at rest, not photons. You need to use the full equation which is
$E^2 = m^2c^4 + p^2 c^2$

 

[Phys_Boi]

$E=mc^2$ only applies to massive particles at rest, not photons. You need to use the full equation which is
$E^2 = m^2c^4 + p^2 c^2$

So what is the momentum of photons since gravitation is applied?

 

[Khashishi]

Set m=0 and you get $E = pc$. You can solve for the momentum of the photon.

 

[Phys_Boi]

Set m=0 and you get $E = pc$. You can solve for the momentum of the photon.

Ah. Thank you

 

[ZapperZ]

Please note that this has been covered and answered in one of our FAQ.

Zz.