In electromagnetic waves, the energy is equally distributed between the electric field and the magnetic field. This is because the electric and magnetic fields are perpendicular to each other and to the direction of wave propagation, and their energies are related by the Poynting theorem, which shows that the energy density of the electric field (ε₀E²/2) is equal to the energy density of the magnetic field (B²/2μ₀).

The speed of electromagnetic waves in a medium is given by c = 1/√(εμ), where ε is the permittivity and μ is the permeability of the medium. This is derived from Maxwell's equations, showing that the wave speed depends on the properties of the medium.

In an electromagnetic wave in free space, the ratio of the electric field amplitude (E) to the magnetic field amplitude (B) is equal to the speed of light, c. This relationship is given by E = cB, derived from Maxwell's equations where c = 1/√(ε₀μ₀).

Radiation pressure on a perfectly absorbing surface due to an electromagnetic wave is given by P = I/c, where I is the intensity of the wave and c is the speed of light. This is because the momentum transferred per unit area per unit time is I/c for complete absorption.

Displacement current arises due to a time-varying electric field. According to Maxwell's correction to Ampere's law, a changing electric field through a surface produces a displacement current, which is necessary for the consistency of electromagnetic theory, especially in capacitors during charging or discharging.

The wave equation E = E₀ sin(kx - ωt) indicates that the wave is propagating in the +x direction. The term (kx - ωt) shows that as time t increases, x must increase to keep the phase constant, indicating propagation in the positive x-direction.

In an electromagnetic wave, the electric field and magnetic field components are in phase with each other (phase difference of 0°). Both fields oscillate in synchrony, reaching their maxima and minima at the same time, as required by Maxwell's equations for wave propagation.

For a perfect reflector, the radiation pressure is P = 2I/c, where I is the intensity of the wave and c is the speed of light. This is because the wave is completely reflected, so the change in momentum is twice that of an absorbing surface, leading to double the pressure compared to absorption.

The Poynting vector (S = E × H) represents the direction and magnitude of energy flow per unit area per unit time in an electromagnetic wave. It points in the direction of wave propagation and its magnitude is related to the intensity of the wave.

The speed of an electromagnetic wave in a medium with refractive index n is v = c/n, where c is the speed of light in vacuum. The refractive index is defined as the ratio of the speed of light in vacuum to the speed of light in the medium, i.e., n = c/v, so v = c/n.