Sinusoidally varying electric fields are generated by all light sources as they are forms of electromagnetic radiation. However, point sources produce spherical waves that do not maintain a sinusoidal form due to their inverse distance dependence. The discussion emphasizes the need for clarity when asking about specific light sources and their electric field characteristics. It is noted that while an infinite plane wave can be mathematically described, no real source can produce such a wave. Instead, arbitrary wave shapes can be represented as a sum of plane wave components.