A plane electromagnetic wave, has frequency of 2.0 × 1010 Hz and its energy density is 1.02 × 10–8 J/m3 in vacuum. The amplitude of the magnetic field of the wave is close to (${1\over4\pi\varepsilon_0}=9\times10^9{Nm^2\over C^2}$ and speed of light = 3 × 108 ms–1) :
(1) 160 nT
(2) 180 nT
(3) 190 nT
(4) 150 nT