The ratio of amplitude of magnetic field to the amplitude

The ratio of amplitude of magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to :

1. the speed of light in vacuum
2. reciprocal of speed of light in vacuum
3. the ratio of magnetic permeability to the electric susceptibility of vacuum
4. unity

The average energy stored in the electric field

U _E =	1	∊₀ E²
	2

The average energy stored in the magnetic field

U _B =	1		B²	,
	2		μ₀

According to conservation of energy U_E = U_B

∊₀μ₀ =	B²
	E²

	B	= √∊₀μ₀ =	1
	E		C