Question

1) Coulomb's Law certainly states that electric forces only exist between electric charges. A truly neutral particle, like a neutron, never experiences an electric force. But can an object that has zero net charge ever experience an electric force? If so, give a concrete example. If not, explain why

2) A capacitor is literally an open circuit: it is two conductors separated by an insulator. If you just cut a wire, technically the two cut ends separated by the air would count as a (very small) capacitor. So how is it possible to talk about "the current through a capacitor"? Shouldn't a capacitor just stop all current flowing through it, just like a cut wire would?

3) Explain in your own words how a Faraday cage works. That is, explain the physical mechanism that causes the electric field within a Faraday cage to be zero.

Answer 1

1.

yes,  an object that has zero net charge ever experience an electric force

example: imagine an electric dipole whose net electric charge is zero. Let an electric diploe be placed in a non-uniform electric field. The diploe now experience a net electric force due to an external field

2.

an electric field is established between the plates of a charged capacitor. the electric field is varying if the charge on the capacitor is varying. the varying electric field in the space between the plates of a capacitor produces displacement current which has similarity with conduction current.

3.

all the charges given to a metallic cage resides on its outer surface and there is no charge in the inner surface. according to Gauss law total electric flux through a closed surface depends on the charge enclosed by the surface. the flux is zero and electric field inside the cage also zero as the cage does not contain at its interior .