My textbook says that no electric field is present inside a metallic cavity.
Let us consider a hollow metallic shell inside another. And if I give a charge (-q) to inner shell, a charge (+q) develops on inner surface of outer shell.
With this much information ,there definitely exists eletric field between the two shells. How do I account for zero electric field inside a metallic cavity when i actually do find an electric field existing?
Am i missing out on any of the other electric fields?
Best Answer
The setup you have described is completely fine and there will definitely be an electric field between the two shells.
But what your textbook means by metallic cavity is that a single metal piece/block with a cavity in it. And metals are conductors, so they will have no charge on their inner surface, all charge would reside on the outer surface only.
Since the charge enclosed in the cavity is 0, by Gauss' law, electric field is also 0. Notice that electric field is also 0 for the inside of any metal object, cavity or not; since charge is only on outer surface.