Electromagnetic waves that are parallel, share a common starting point, have the same frequency and phase, and move through the same medium, form an advancing wavefront at right angles to their direction of travel.
- A wavefront is a conceptual tool used in to study waves, including electromagnetic waves like light. It refers to the locus of all points in phase with each other along the wave at a given instant. In other words, it represents the leading edge of a wave as it propagates through a medium.
- Sources that emit light in all directions, known as point sources, generate spherical wavefronts.
- Lasers, which produce a narrow beam of parallel rays, create waves with flat wavefronts.
- An electromagnetic wave with a flat wavefront is known as a plane wave.
- In addition to plane waves and spherical waves, there are also cylindrical waves produced when a point source is extended along a straight line.