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

Ultraviolet (UV) waves are the primary electromagnetic radiation used for detecting forgery in currency notes. Genuine banknotes incorporate specialized security features, such as luminescent materials and fluorescent fibers, which are invisible under normal light but emit specific colors and patterns when exposed to UV-A light [2]. This process, known as fluorescence, allows for quick and reliable authentication in banks and retail environments. While modern currency management involves various security enhancements, UV light remains a standard tool because counterfeit notes often lack these specific fluorescent markers or emit incorrect colors. Although research into microwave technology for identifying markers exists, UV detection is the most widely established and practical method for verifying the authenticity of banknotes and other security documents [3].

Sources

1. [2] https://pmc.ncbi.nlm.nih.gov/articles/PMC8398156/
2. [3] https://pmc.ncbi.nlm.nih.gov/articles/PMC9571956/