In an electromagnetic wave, the electric field peak magnitude E and the magnetic field peak magnitude B are related by
[tex]E=cB[/tex]
where [tex]c=3 \cdot 10^8 m/s[/tex] is the speed of light. Substituting [tex]E=0.39 \cdot 10^{-4} v/m[/tex], we can find the peak magnitude of the magnetic field:
[tex]B= \frac{E}{c}= \frac{0.39 \cdot 10^{-4} v/m}{3 \cdot 10^8 m/s} =1.3 \cdot 10^{-13}T[/tex]
