Light Waves, Photons

Abstract

Many important aspects and phenomena of quantum mechanics can be visualized by means of wave mechanics, which was set up in close analogy to wave optics. Here the simplest building block is the harmonic plane wave of light in a vacuum describing a particularly simple configuration in space and time of the electric field E and the magnetic induction field B. If the x axis of a rectangular coordinate system has been oriented parallel to the direction of the wave propagation, the y axis can always be chosen to be parallel to the electric field strength so that the z axis is parallel to the magnetic field strength. With this choice the field strengths can be written as

$$ \begin{gathered} {E_y} = {E_0}\cos \left( {t - kx} \right),\quad {B_z} = {B_0}\cos \left( {wt - kx} \right), \hfill \\ {E_x} = {E_z} = 0,\quad \quad {B_x} = {B_y} = 0 \hfill \\ \end{gathered} $$

They are shown in Figures 2.1 and 2.2. The quantities E ₀ and B ₀ are the maximum values reached by the electric and magnetic fields, respectively. They are called amplitudes. The angular frequency ω is connected to the wave number k by the simple relation

$$ w = ck $$