In neutron electric charge is distributed?

Question

a) negative inside, positive ouside
b) neutral everywhere
c) positive inside, negative outside

"Physicists have long known that neutrons are slightly positive at the core and slightly negative at the surface..."

How on Earth did they learned that?

Answer 1

I don't think it's B, because a neutron converts to a proton during beta minus decay, ejecting an electron and an anti-neutrino. I would guess C.

Answer 2

It's C. Neutrons have a slightly positive core, and an negatively charged outer shell. The observation has not yet been explained in a fully satisfactory manner, but it must result from a preferred average spatial orientation of the 3 quarks that comprise a neutron.

The spatial distribution of a neutron's charge is determined from electron-scattering experiments. See source.

Answer 3

I can answer the "How on Earth did they learned that?" follow-up. With scattering experiments! If the charge density were uniformly zero, for example, the scattering cross section for electrons would be zero. Any nonuniformity, and electrons start to scatter. A detailed measurement of the *differential* elastic scattering cross section (angular probability distribution) can be inverted to provide the internal charge distribution.

Why do think they spend all that money building bigger and bigger accelerators? To see what's inside!

Answer 4

Aneutron is a constriction of a proton plus an electron mass.
Charge is something that the world of physics has never really defined.
However the neutron is called neutron becaus its so heavy that it cannot be deflected by lighter masses such as electrons.
It is the proton that locks with the neutron in the nucleous of the atom. Basically the word charge is just a matter of convention rather than definiton.