Question

A thin sheet of paper of dielectric constant ϵ=2.5 is placed in a uniform electric field of magnitude 20 stat volts/cm. Use the boundary conditions to obtain an approximate value for the electric field inside the paper.

a) Assume that the paper is parallel to the electric field.

b) Assume that the paper is perpendicular to the electric field.

A thin sheet of paper of dielectric constant ε--25 is placed in a uniform electric field of magnitude 20 statvolts/cm. Use the boundary conditions to obtain an approximate value for the electric field inside the paper. (a) Assume that the paper is parallel to the electric field. (b) Assume that the paper is perpendicular to the electric field.

Answer 1

In the absence of free charges,

$\epsilon_1E_1^{\perp}=\epsilon_2E_2^{\perp}$

and

$E_1^{\parallel}=E_2^{\parallel}$

(a) 20 V/cm

(b)

$2.5\times E=1\times20$

$E=8\textup{ V/cm}$