The light source of LED light tube uses LED as luminous body. The gas between the two filaments emits ultraviolet light when it conducts electricity, causing the phosphor to emit visible light. Leds provide monochromatic light with a large half-width. Since the energy gap of semiconductors decreases with increasing temperature, the peak wavelength emitted by leds increases with increasing temperature. LED light tube is generally used for general lighting, office buildings and other indoor lighting and so on.