EM wave reflection at conducting surface with boundary conditions

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Homework Statement


EM Waves propagating through vacuum towards the x-direction approaches a conducting surface at x = 0.

Part (a): Prove the following relations. Find the boundary conditions for [tex]E[/tex] and [tex]B[/tex] if charge density [tex]σ[/tex] and current density [tex]s[/tex] exists on the surface.

Part (b): Find [tex]B[/tex] in terms of [tex]E_0[/tex]

Part (c): Show the reflected wave has the following form:

Part (d) Find magnetic field of reflected wave and [tex]s[/tex]

Homework Equations


The Attempt at a Solution



Part(a)
Handwritten part (a) with four numbered boundary conditions: E1 parallel = E2 parallel; E1 perp minus E2 perp = sigma/epsilon0; B1 perp = B2 perp; and (1/mu1)B1 parallel minus (1/mu2)B2 parallel = s. Beside it, a sketch of a wave vector k at angle theta to the x-axis, with E and B field vectors, and an x-y-z axis diagram with a shaded surface.


Part(b)
Handwritten derivation of plane-wave fields: k vector = k(cos θ, sin θ, 0), E = E0(-sin θ, cos θ, 0) times exponential of i(k·r - ωt), B0 = (kE0/ω)(cos θ, sin θ, 0) cross (-sin θ, cos θ, 0), reducing to (kE0/ω)(0, 0, 1). Red sketch of k, E and B vectors; black sketch of z, y and x axes with a shaded wave-front region.


Part(c)

This is the part that disturbs me. I assumed the free current s = 0 and σ = 0. Usually [tex]k[/tex] would be perpendicular to the surface, making derivations easier.

I actually got perpendicular reflected E-field = 0, which is wrong..
But, I got parallel reflected E-field = - incoming parallel E-field, which is right

Handwritten derivation of boundary conditions for EM waves at a conducting surface, including B1 and B2 relations, E-field relations with beta = K2 c mu1 / (omega mu2), and results for reflected E-fields.


I'm confused - If it's a perfect conductor it should have no free charge or currents, but the question says it does. Then again, in order to derive the reflected e-field, we need to assume they are 0.