# I Exchange of photons inside atoms

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1. Nov 27, 2016

### CassiopeiaA

I was reading Feynman Diagrams and stumbled upon this query: If the electrons and protons interact by exchange of photons, does the electron inside an atoms also interact with the nucleus with a similar kind of exchange?

2. Nov 27, 2016

### hilbert2

In a simplified model of the hydrogen atom, which you encounter in a first QM course, we have a particle of reduced mass $\mu = \frac{m_p m_e}{m_p + m_e} \approx m_e$ moving in a potential that's proportional to $\frac{1}{r}$. However, in a more advanced and detailed treatment the system consists of an electron, a nucleus and the electromagnetic field, which are all seen as dynamical entities. In the advanced model, the interaction between the nucleus and the electron indeed happens through exchange of photons (excitations of the EM field).