What kind of spectra is produced by low pressure gas that is excited by heat or electricity?

The type of spectrum produced by low pressure gas that is excited by heat or electricity is known as emission spectra. When a gas is heated or subjected to an electric field, its atoms or molecules gain energy. This energy is transferred to the electrons, which then occupy higher energy levels. When the electrons return to their original (lower) energy levels, they release this energy in the form of light.

This emitted light is specific to the particular elements present in the gas, resulting in a series of distinct wavelengths of light rather than a continuous range. Each element emits light at characteristic wavelengths, which are observed as bright lines on a dark background when analyzed through a spectroscope. This phenomenon forms what is known as an emission spectrum.

In contrast, absorption spectra occur when light passes through a cooler gas; certain wavelengths are absorbed, leading to dark lines on a continuous spectrum background. Continuous spectra are produced by solid, liquid, or densely packed gases, where light is emitted uniformly across a range of wavelengths without specific lines. Reflection spectra relate to the light reflected off surfaces and are not applicable in this context of excited gases.