Which one of the following waves is used for detecting forgery in curr

Which one of the following waves is used for detecting forgery in currency notes ?

Ultraviolet waves
Infrared waves
Radio waves
Microwaves
This question was previously asked in
UPSC NDA-2 – 2017
Many modern currency notes incorporate security features that are visible under ultraviolet (UV) light. These features often include fluorescent threads, watermarks, or specific inks that glow or change color when exposed to UV radiation. Checking currency notes under UV light is a common method used to detect counterfeits that lack these specialized security features.
– Ultraviolet (UV) light is used to reveal fluorescent security features in currency notes.
– These features are difficult to replicate by counterfeiters.
Infrared (IR) waves are also used in some advanced currency verification systems, as some inks have specific absorption or reflection properties in the IR spectrum. However, UV light inspection is a more common and basic method for detecting forgery in widely circulated currency. Radio waves and Microwaves are not typically used for visual security checks on currency notes.