What type of gas will give off light when current passes through it?

When an electric current passes through a gas, the gas can become ionized, leading to the emission of light as electrons move between energy levels. Neon is well-known for producing a bright, characteristic reddish-orange light when a current flows through it. This phenomenon occurs because the energy supplied by the electric current causes the neon atoms to emit photons, which we perceive as visible light.

While other gases like argon, helium, and xenon can also emit light under certain conditions, neon is particularly recognized for its application in neon signs and lighting, making it the most commonly associated gas in this context. The distinct color and efficiency of neon in producing light makes it a favored choice for illumination in various applications, distinguishing it from the other options listed.