Money Detector

When we placed the bill under the lamp (the device that let us know if the bill is genuine or fake), some parts of the bill glow and reveal interesting marks. The marks are called fluorescent prints and they fluoresce or glow when exposed to the lamp.
The money detector has a special bulb called the UV lamp or black light. This emits ultraviolet light which causes the fluorescent dye on the bill to light up. Fluorescent marks usually portray the denomination of the bill. The dye is also incorporated in the serial numbers and security fibers. This causes them to glow as well.