Police Sergeant Practice Exam

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Invisible laundry marks are usually discovered using what tool?

Magnifying glass
Thermal imager
Ultraviolet lamp
Standard flashlight

The correct answer is: Ultraviolet lamp

Invisible laundry marks are typically revealed using an ultraviolet lamp. This tool is particularly effective because many laundry markers contain fluorescent inks that only become visible under UV light. The ultraviolet wavelengths can cause these special inks to fluoresce, making them stand out against the fabric’s background color. Other tools like a magnifying glass or standard flashlight may assist in examining fabric for clarity and detail but do not have the capability to make invisible markings appear. A thermal imager is used for detecting heat signatures rather than ink properties, making it unsuitable for discovering invisible marks. The use of an ultraviolet lamp is a common investigative technique in various contexts, including forensic examinations, because of its ability to uncover information that is not visible to the naked eye.