Final answer:
UV light is the dermal light that can be used to protect the skin against bacteria. It causes the formation of thymine dimers in bacterial DNA, leading to their death. Other natural defense mechanisms in the skin also protect against bacteria.
Step-by-step explanation:
The dermal light that can be used to protect the skin against bacteria is UV light. Sunlight consists of a broad spectrum of light, including UV light and visible light. UV light can effectively protect the skin against bacteria by causing the formation of thymine dimers in the DNA of bacteria, which disrupts their replication and kills them.
It's important to note that the skin has its own natural defense mechanisms against bacteria, such as immune system cells called Langerhans cells and the presence of antimicrobial substances. However, UV light can provide an additional protective measure.
UV light can be obtained from sunlight, but it's important to take precautions to avoid excessive exposure, such as using sunscreen and limiting sun exposure during peak hours.