What is true about invisible light in relation to its visibility and effects on skin?

Invisible light refers to light that cannot be seen by the human eye, such as ultraviolet (UV) light and infrared light. While this type of light is not visible, it can still have significant physical effects on the skin. For example, UV light can cause skin damage, sunburn, and even lead to skin cancer, while infrared light may produce heating effects that can be beneficial in certain therapeutic treatments.

The correct answer highlights that although invisible light cannot be seen, it is capable of producing these physical effects on the skin, which is essential knowledge for estheticians. Understanding the various types of light and their interactions with skin is critical for effective skin care practices and treatments.

The other choices present misconceptions: while some forms of invisible light can be harmful, they are not universally to be avoided; not all invisible light is visible and beneficial would be an inaccurate representation of its effects, and saying it cannot penetrate the skin overlooks its ability to interact with skin layers.