Consider an electromagnetic wave propagating through a region of empty space. How is the energy density of the wave partitioned between the electric and magnetic fields? Consider an electromagnetic wave propagating through a region of empty space. How is the energy density of the wave partitioned between the electric and magnetic fields? The energy density of an electromagnetic wave is equally divided between the magnetic and electric fields. The energy density of an electromagnetic wave is 25% in the magnetic field and 75% in the electric field. The energy density of an electromagnetic wave is 25% in the electric field and 75% in the magnetic field. The energy density of an electromagnetic wave is entirely in the magnetic field. The energy density of an electromagnetic wave is entirely in the electric field.