Question

Where does energy come from in fusion/fission?

Answer 1

$<b>When fusion occurs in the sun, its due to quantum tunneling causing hydrogen atoms to bind, forming helium. Energy isreleased because two hydrogen atoms have more energy then one helium atom, and when they bind the excess is released into space. The energy itself comes from some of the mass deteriorating into photons.$

Answer 2

Let ZZ be the number of protons, NN the number of neutrons, and A=N+ZA=N+Zthe atomic number. The "volume" of the drop scales as AA, the "surface area" scales as A2/3A2/3, and the "radius" and typical interparticle separation scale as A1/3A1/3. Coulomb repulsion therefore scales as Z2/A1/3Z2/A1/3, but there are other energy considerations. In general, we expect the binding energy to be something like

EB=aVA−aSA2/3−aCZ2A1/3−aA(N−Z)2A+χaP1A1/2,EB=aVA−aSA2/3−aCZ2A1/3−aA(N−Z)2A+χaP1A1/2,