 The magnetic field is related to the electric field through Faraday's law (cgs units)

The plane sinusoidal solution for an electromagnetic wave traveling in the z direction is (cgs units and SI units)

formula_4

for the electric field and

for the magnetic field, where k is the wavenumber,

is the angular frequency of the wave, and formula_7 is the speed of light.The hats on the vectors indicate unit vectors in the x, y, and z directions.In complex notation, the quantity formula_8 is the amplitude of the wave.