When we want to view the spectrum of light emitted by a certain gas (via spectroscopy) how much voltage do those gas discharge tubes end up having? I know they are very high voltage, but how high exactly? Now if I were to look at an incandescent light bulb through a spectroscope, I would see the full, continuous spectrum of light. Since light bulbs do contain some inert gas (like krypton), why don't we see the spectrum emitted by the krypton itself? Is it because light bulbs are usually low pressure? Is it because the voltage is only 120 V? This is my guess: I know that an LED will emit a much "fuller" and "clearer" spectrum than a regular light bulb will. I am guessing that since the gas inside a light bulb is low pressure, there isn't enough of it to emit that specific gas' spectrum only. I would also guess that because there is insufficient voltage to cause the electrons to jump around in the energy levels of the krypton, we also don't see the discrete lines. Since an LED does not use a gas filled tube like a bulb does, the spectrum is much more complete. The low pressure gas inside a light, is not enough to show its discrete emission spectra. Moreover, the fact that we only have a small amount of that gas, this is what cases the light from a bulb to be less complete than the light from an LED. If someone could help me with my questions I would appreciate it.