Fluorescent Light
Visible light produced when phosphor is hit by ultraviolet light
Real World Example
Imagine trying to read a book in the dark without a flashlight; you can't see the words until you shine a light on the page. Similarly, in a fluorescent light, the phosphor coating inside the tube remains invisible until it is "illuminated" by ultraviolet (UV) light. Just as the flashlight reveals the words on the page by shining light on them, the UV light excites the phosphor, causing it to emit visible light that brightens the room.
Practice Version
