Physics

Problem

The average energy density associated with the electric field of a plane electromagnetic wave in vacuum is

7.8 \times 10^{-9}\,\text{J m}^{-3}

. Take

\varepsilon_0 = 8.85 \times 10^{-12}\,\text{C}^2\text{N}^{-1}\text{m}^{-2}

and

c = 3.0 \times 10^{8}\,\text{m s}^{-1}

. Estimate the amplitude

B_0

of the magnetic field. a)

4.4 \times 10^{-7}\,\text{T}

1.3 \times 10^{-7}\,\text{T}

2.0 \times 10^{-7}\,\text{T}

1.0 \times 10^{-7}\,\text{T}