5. A positive point charge Q is at the center of a spherical dielectric sphere with radius of R. The material of this dielectric sphere is simple medium with relative permittivity of εᵣ. Please evaluate the equivalent polarization surface charge density (or bound surface charge density) of the surface of the sphere. (A) 0 (B) (C) (D) None of the above

3. A lossy dielectrics (conductivity = σ, absolute permittivity = ε) is placed between two parallel perfect metal plates, as shown in the figure below. The areas of the metal plates are A (A = W×L). The distance between the metal plates is d and is much smaller than the length or width of the metal plates (d ＜＜ W and d ＜＜ L). Applying a voltage V₀ between the perfect metal plates, please evaluate the ratio between the storage energy and dissipated power of this structure (Estorage/Pdiss). (A) (B) (C) (D) None of the above

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