Electromagnetism – Dielectric

An infinite slab of insulating material with dielectric constant K and permittivity ɛ = Kɛ₀ is placed in a uniform electric field of magnitude E₀. The field is perpendicular to the surface of the material. The magnitude of the electric field inside the material is 

A. E₀/K
B. E₀/Kɛ₀ 
C. E₀
D. Kɛ₀E₀
E. KE₀

(GR0177 #95)

Solution:

In vacuum, E₀ = σ/ɛ₀
In dielectric, E = σ/ɛ
where ɛ = Kɛ₀
Thus, E = σ/Kɛ₀ = E₀/K

Answer: A