Why the electric field inside a metal sphere carrying a charge Q is zero?

I was solving some problem regarding the polarization during this I came across an example 4.5 in Griffith's where it is written that the Electric field inside the metal sphere carrying a charge Q is zero . The metal sphere is surrounded by a dielectric material

Is there any effect of the material which has surrounded the metal sphere due to which it's electric field inside the sphere becomes zero.

Can anyone explain me about these things? I literally confuse among the situations that where the electric field should be zero or not.

The Charge Q always stays on the surface of metals because any net charge resides on the surface. So there is no charge density inside the metal sphere. i.e. ρ = 0. So applying Gauss's Law would give you: $E=0$.
• I would like to know how you go from $\rho = 0$ to $E = 0$. In general there can be an electric field even in regions where there is no charge density, such as in the vicinity of stationary point charge, or in the presence of an electromagnetic wave. One has to be careful when reasoning that there is no field inside a conductor. Jul 2 '18 at 15:35