The Fluorescent Tube is an item and entity added by Immersive Engineering. Right-clicking it will place it.
If inside the range of a Tesla Coil, it will glow.
The color of a Fluorescent Tube can be adjusted inside an Engineer's Workbench. Additionally, a Fluorescent Tube can be rotated by right-clicking or shift right-clicking it with an Engineer's Hammer (shift right-clicking will make it rotate faster).