【Principle of Luminescence】Based on the phenomenon of low-pressure discharge, different gases are filled into a vacuum glass tube, and a voltage is applied across its ends to induce a glow discharge in the gas, thereby emitting light of a specific color. 【6 Spectral Tubes】During the experiment, use a metal rod to connect to the top electrode of any spectral tube, causing the gas inside the tube to undergo glow discharge. Different spectral tubes emit spectra of varying colors and shapes. 【Procedure】Connect one end of the induction coil or high-voltage power supply to the electrode connected to the base, and connect the other end via a wire to the metal rod with an insulated handle. 【Luminescence Phenomenon】Since various gaseous elements or compounds possess their own characteristic emission lines or spectral bands, their spectral states can be observed through a spectroscope. 【Applications】Spectral tubes are primarily used to observe the emission spectra of gases. They are commonly employed in laboratories and research settings to aid in the analysis of gas composition and properties.