Lesson 2 – Wave-Particle Duality

Light is an EM wave, and every wave has specific properties. The basic properties of a wave’s amplitude, direction, and length each lead to different phenomena. An optical source’s intensity or power level are due to the amplitude of the wave’s vibrations. The polarization of light is dictated by the direction its waves oscillate with respect to the direction it travels. Finally, the color of light is given by the length of its waves (wavelength); this is the separation between a wave’s consecutive crests and valleys.

Though light has the properties of a wave, it travels so fast it may be modeled as a beam or ray of light. This duality—the ability to be observed as either a ray or a wave—is a fundamental aspect of light. Consider a two-dimensional field of light coming at you. If a surface is constructed that connects common points along the light’s oscillation, known as phase points (either a crest or a valley, for instance), the result is a wavefront of light. A perpendicular may be drawn to these wavefronts to point the direction the light is moving. This maps a wavefront of light into the direction of a ray of light.