Spectrum tubes operate by passing electric current through gas-filled sealed tubes, causing them to emit light. Common applications include fluorescent lamps, which utilize this principle to produce illumination. The discussion also touches on the relationship between electric currents, gas excitation, and the resulting wavelengths of light, including visible and non-visible spectra like ultraviolet and infrared. Participants explore connections to educational topics such as diffraction grating and spectrometry, emphasizing the importance of understanding wavelengths. Overall, the conversation highlights the practical uses of spectrum tubes in lighting and scientific measurement.