Where does E=mc^2 fit in to E=hv=hc/

[golgiapparatus88]

Title says it all.

I know the two big equations you need for energy of a photon are E=hf and E= hc/λ, but where does E=mc^2 fit in to that? Should the energy be the same as long as all the variables are constant?

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[starbaduk]

Title says it all.

I know the two big equations you need for energy of a photon are E=hf and E= hc/λ, but where does E=mc^2 fit in to that? Should the energy be the same as long as all the variables are constant?

I think typical place you would use E=mc^2 is for nuclear binding energy. When nucleons bind, they lose some mass. The energy required to separate the bound nucleus into individual nucleons is equal to mc^2 where m is the mass lost.

 

[golgiapparatus88]

ohhhh that's right. Thanks

 

[Pisiform]

ok so,

E = hv and E = mc^2

so,

hv = mc^2
hc/λ = mc^2
(c cancels out)

so, h/λ = mc

This is De Broglies Equation