How does ultraviolet light assist in crime scene investigations?

• A. It detects the presence of radioactive substances.
• B. It shows cold areas as blue and warm areas as red.
• C. It causes substances to fluoresce and give off visible light.
• D. It transmits information to AM and FM radio receivers.

Answer: (C)

Ultraviolet light plays a crucial role in crime scene investigations primarily because it causes certain substances to fluoresce. When these substances, such as bodily fluids, certain fibers, or trace materials, are exposed to ultraviolet light, they absorb the UV radiation and then re-emit it as visible light. This fluorescence can help forensic investigators locate and analyze evidence that may not be visible under normal lighting conditions.

In practice, this means that things like blood, semen, and saliva can become illuminated, making it easier to identify and collect forensic evidence. The ability to see these substances not only aids in locating them but also can provide important information regarding a crime. The use of UV light in this context is a powerful tool that enhances the investigative process and increases the likelihood of solving crimes.