# Cause of energy release in fusion [duplicate]

For the fast few months, I have been scratching my head for this problem which I have faced while studying fusion.

In a hydrogen fusion, two hydrogen (for instance ) fuse to form a helium nucleus. I have heard that the hydrogen nuclei have negative potential energy due to interactions between the electron and proton electrostatic field.

Doubt 1 --》 can anyone explain me that what are the ideal conditions for negative potential energy which results in mass defect (right?)

Continuing, the nuclei fuse to form a helium nucleus which hass less mass than its reactants. Also nucleons in a helium nucleus experience more nuclear force between each other. What accounts for the increase in the energy which has to have an energy origin? Also combining all and taking in $$E=mc^²$$, HOW can we explain that nuclear fusion releases energy?

• Does this answer your question? Binding energy and mass May 20 at 5:38
• Hi Hardik. I think the question I've linked is the same as your question. If you don't think it answers your question you can edit your question to make it clear what hasn't been answered and I'll vote to reopen. May 20 at 5:40
• The potential energy represented by the electrostatic attraction between a nucleus and its orbital electrons can be partly released through chemical reactions, but this has no connection with the nuclear binding energy holding nucleons together in a nucleus, which is many times greater. Nuclear binding energy provides the energy released in nuclear fusion. May 20 at 5:45
• @JohnRennie , the answer of yours was excellent. I understood the whole mathematics of it but if you were to explain it in theory rather than in equations which may include the energy released during nuclear fusion in terms of E=MC² and also the transition of binding energy explanation, it would be as if I have solved the damn problem forever....Kindly help me. Your answer was very exceptional once again. Can you also include an example of hydrogen fusion to helium? I don't know any way to edit my question. :C May 20 at 10:01
• @hardik The four nucleons in a helium nucleus are held together by the strong force. To separate the nucleons you would have to add energy - like stretching a spring. This energy is the binding energy of the nucleus. If you reverse the process and (somehow) create a helium nucleus from four separate nucleons then this same amount of energy is released - just as energy is released if a stretched spring is relaxed. May 20 at 10:02