Final answer:
Neon signs produce a discontinuous or line spectrum, emitting light at specific wavelengths unique to the gas inside, creating a series of bright lines rather than a continuous spectrum of colors.
Step-by-step explanation:
Neon signs have a discontinuous or line spectrum rather than a continuous spectrum. The spectrum produced by a neon sign is the emission spectrum of the neon gas within the sign. Exciting neon gas in the sign by electrical discharge causes the gas to emit light at specific, discrete wavelengths, producing a series of bright lines rather than a continuous range of colors. This is distinct from an incandescent lightbulb, which produces a full continuous spectrum of light. Each element has its own unique pattern of emission lines, which is why neon signs can be made in different colors by using gases other than neon.
The familiar red-orange light of neon signs is due to the specific emission spectrum of neon gas, resulting from electrical excitation of the neon atoms. When other gases are used, such as mercury or sodium, different characteristic colors are produced, such as blue or yellow respectively, again due to their own unique emission line spectra.