## E = mc2 [ENDORSED]

$\lambda=\frac{h}{p}$

GevickSafarians_14B
Posts: 19
Joined: Sat Jul 09, 2016 3:00 am

### E = mc2

If E = mc2 is the energy of a photon, shouldn't wee need the mass of a photon to calculate this? This means photons have a mass, but only when they are moving and producing kinetic energy? But, they have no rest mass?

Cliff Danza 3F
Posts: 20
Joined: Wed Sep 21, 2016 2:57 pm
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### Re: E = mc2  [ENDORSED]

E=mc^2 is a formula used for matter. Photons do not have a mass, so the equation to calculate their energy is: E=(h*c)/lambda.