In a nucleus, two protons exert an electromagnetic force on each other and if they are able to break the electrostatic repulsion barrier they exert nuclear force on each other. I know that neutrons are effective in binding the nucleus as they effectively break the electrostatic barrier as they have no charge and thus are easily able to exert a force on the protons to bring them together.Is the electromagnetic attractive force between the neutron and proton also a contributing factor?Does a neutron exert electromagnetic force on a proton as well or only nuclear force,in an atom?
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1$\begingroup$ There is no electromagnetic attractive force between the proton and the neutron. There are strong forces, however. The neutron sits between two protons and glues them together. It also increases the distance between the two which helps in reducing the electromagnetic force between two protons. $\endgroup$– YashasCommented Mar 11, 2017 at 8:30
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$\begingroup$ Related: What is the strong nuclear force between proton and neutron in a deuteron? $\endgroup$– YashasCommented Mar 11, 2017 at 8:31
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3$\begingroup$ Protons and neutrons are made out of quarks, so we could say that in a sense there is electro-magnetic field interaction; but the superposition of the electric fields from the neutron's quarks is so small because positive quarks' field will cancel negative quarks' field, so overall, there will be almost no big enough electromagnetic interaction in the sense of Coulomb force (practically 0). But the field superposition will be there none the less, even if the sum is 0. $\endgroup$– Mihai B.Commented Mar 11, 2017 at 9:27
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$\begingroup$ Another way of looking at the E&M force between neutrons and protons is via their anomalous magnetic moments. So there is no coulomb interaction between them but they do interact magnetically. $\endgroup$– Lewis MillerCommented Mar 11, 2017 at 16:20
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3 Answers
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The quarks within a nucleon, proton or neutron, are charged, but the ones in the neutron add up to over all charge 0.
The nucleons though are complicated because of the strong interaction which has a sea of quarks antiquarks and gluons within the nucleon bag, so there will be a charge distribution within the neutron which in some models is calculated to be negative in the center ( so positive on the ouside), so it would be a repulsive force with the proton charges.
What saves the day is the magnitude of the coupling constants. The strong QCD force is of order 1, the electromagnetic of order 1/137 and the multiple vertices in the inevitable many body problem Feynman diagrams will reduce the effect by orders of magnitude.
The spin effects will be more visible, in the way the protons and neutrons are organized within a nucleus, and has to be taken into account in the nuclear models, individual magnetic moments adding up to the magnetic moment of a nucleus.
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There will be electromagnetic force in between, the protons will repulse each other, but the strong force is so strong that it keeps the protons and nutrons inside the nucleus.
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Well the protons and neutrons mostly interact with the strong force. However the neutron has a magnetic moment so this can cause neutrons and protons interact electromagnetically. However this is going to be very very very weak compared to strong force. The protons are also held together by strong force. Electromagnetism mainly interacts between protons where there is a charge of +1. Neutrons mostly exert nuclear force or strong force between other protons and neutrons(nucleons).
