Consider a scenario where a$|$composite material is made by combining a conductor $($copper$)$ and a dielectric $($silicon dioxide$).$ This composite material is placed in a uniform external electric field of magnitude $E_0.$ Analyze the behavior of the electric field within both materials considering their boundary conditions. Specifically, address the following points in your analysis:

Describe how the electric field behaves at the interface between the copper and silicon dioxide.

Explain the impact of the dielectric's permittivity on the electric field distribution.

Calculate the resultant electric field within each material, assuming that the external field is perpendicular to the surface of the conductor.

Provide your analysis using appropriate equations and diagrams to illustrate the field distributions and interfaces.