What is electromagnetic radiation?
A beam of light is a traveling wave of electric and magnetic fields. These fields vary sinusoidally and vary with the same frequency and in phase with each other.
The electric and magnetic fields, E and B, are always perpendicular to the direction of travel of the wave. Electromagnetic waves are transverse waves.
E and B are always perpendicular to each other.
The cross-product, E x B, gives the direction of propogation of the wave.
The oscillating magnetic field induces the electric field, and the oscillating electric field induces the magnetic field.
Courtesy of Case Western Reserve University http://abalone.cwru.edu/
For the purpose of mineral optics we need only focus on the oscillating electric field.
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