The energy density associated with electric field E and magnetic field B of an electromagnetic wave in free space is given by (ε₀ = permittivity of free space, μ₀ = permeability of free space):
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Question

The energy density associated with electric field E and magnetic field B of an electromagnetic wave in free space is given by (ε₀ = permittivity of free space, μ₀ = permeability of free space):

G1 Physics · Accepted Answer

For an electromagnetic wave in vacuum: Electric energy density: u(E) = (1/2)ε₀E² Magnetic energy density: u(B) = B²/(2μ₀) These are the standard instantaneous energy-density expressions. Hence option A follows.