What causes an absorption line spectrum

The warm earth then radiates this heat at longer infrared wavelengths. When a high enough voltage is applied across the tube, the gas ionises and acts like a conductor, allowing a current to flow through the circuit. The transistions are grouped into a series based on the lowest level involved in the transition.

The tube is filled with a gas. And why do they emit only energy of these same wavelengths? Energy of transition absorption from Energy Level 2 to Energy Level 3: Diagram of a discharge tube.

The minus sign means that absorption is occurring. Diagram of the emission spectrum of hydrogen in the visible spectrum. The answers lie in quantum mechanics.

An emission line is formed when the electron falls back to a lower energy state, releasing a photon. As the photons of light are absorbed by electrons, the electrons move into higher energy levels. The gaps correspond to energies wavelengths for which there is a corresponding difference in energy levels for the particular element.

Kirchhoff's Laws

In the absorption spectrum there will be gaps. The following needs to be in your answer: The diagram on the next page demonstrates absorption and emission of photons by an atom using the Neils Bohr model of a hydrogen atom, where the varying energy levels of the electron are represented as varying orbits around the nucleus. You have learnt previously about the structure of an atom. Look at the two figures below.

In the first diagram are shown some of the electron energy levels for the hydrogen atom. For example, the light from a distant galaxy that is moving away from us at some velocity will appear redshifted.

I have an unknown gas in a glass container. Atoms do not only emit photons; they also absorb photons.

Absorption/emission lines

If a large enough voltage difference is applied between the two metal plates, the gas atoms inside the tube will absorb enough energy to make some of their electrons come off, i. Spectroscopy is a tool widely used in astronomy to learn different things about astronomical objects.

The varying series of absorption and emission lines represent different ranges of wavelengths on the continuous spectrum. In the early 1900s, scientists found that a liquid or solid heated to high temperatures would give off a broad range of colours of light.