The phase difference between e(z,t) and h(z,t) vanishes when conductivity is zero, (A).
What occurs in this phase?
The phase difference between the electric field (e(z,t)) and the magnetic field (h(z,t)) in an electromagnetic wave depends on the wave's propagation characteristics, primarily the conductivity (σ) of the medium it travels through.
When conductivity is non-zero (σ>0), the electric field interacts with the medium, causing energy dissipation and a phase lag between the electric and magnetic fields. This lag becomes more significant as conductivity increases.
Therefore, only when conductivity is zero will the phase difference between the electric and magnetic fields vanish.