1. Neon Sign: Neon signs are a classic example. When electricity passes through a tube filled with neon gas, the gas atoms get excited. As they return to their ground state, they emit specific wavelengths of light, creating the characteristic reddish-orange glow. This emission is a line spectrum because only specific wavelengths are emitted.
2. Sodium Vapor Lamp: Sodium vapor lamps are common for street lighting. Similar to neon signs, they use a gas (sodium vapor) that gets excited by electricity. The excited sodium atoms release specific wavelengths of light, mainly a bright yellow line corresponding to the D-line of sodium. This distinct yellow color is a result of the line spectrum emitted by the excited sodium atoms.
