Find the energy density uₑm and the Poynting vectors in the gap. Note especially the direction of s. Check that eq. 8.12 is satisfied.
a) uₑm = (1/2)ε₀E², S = ε₀cE²
b) uₑm = ε₀E², S = (1/2)ε₀cE²
c) uₑm = (1/2)cE², S = ε₀E²
d) uₑm = (1/2)ε₀cE², S = E²