Electric energy density is equal to the magnetic energy density
Electric energy density is half of the magnetic energy density
Electric energy density is double of the magnetic energy density
Both electric and magnetic energy densities are zero
During the propagation of electromagnetic waves in a medium: Electric energy density UE=1/2εE2. Now using B=E/c and c=1/√με, we get UE=1/2εE2=1/2B2/μ=UB. Electric energy density is equal to the magnetic energy density.