Which term describes light waves that are parallel and in phase?

The term that describes light waves that are parallel and in phase is coherent light. Coherent light is characterized by having a consistent phase relationship and the same frequency, which means that the waves maintain a constant difference in phase over time. This quality allows coherent light to exhibit properties such as interference and the potential for creating well-defined patterns, which are essential in applications like laser technology.

In contrast, divergent light refers to light rays that spread out from a point source. Incoherent light consists of waves that are not in phase with one another, leading to random phase relationships and a lack of consistent interference patterns. Polarized light, on the other hand, describes light waves that oscillate in a specific direction rather than randomly, but it does not imply that the waves are necessarily in phase. Thus, coherent light is distinct in its parallel and in-phase nature, making it the correct choice for this question.