Washington Esthetician State Board Practice Exam 2026 – Complete Prep Resource

Natural sunlight consists of a spectrum of electromagnetic radiation, which includes ultraviolet light, visible light, and infrared light. Visible light is the portion of this spectrum that the human eye can perceive and is essential for processes such as photosynthesis in plants and for our own vision.

The amount of natural sunlight that is made up of visible light is typically around 40% to 50% of the total solar radiation that reaches the Earth’s surface. While different studies may present slightly varying figures, the consensus indicates that the percentage is closer to 50%. Thus, if we look at the provided options, the figure identified as 65% exceeds the typical range and does not align with standard estimations provided in scientific literature.

Understanding that about half of sunlight is visible light serves not only as a foundational concept in esthetics—particularly when discussing treatments like light therapy—but also emphasizes the importance of protecting the skin from excessive UV exposure while still benefiting from visible light's effects.