Dark narrow lines that represent absorption of energy at a particular wavelength of light: Absorption lines can be exemplified by each of the elements on the periodic chart which absorb energy at specific wavelengths of light, and that looks like a bar code.

The magnetic equator which is an imaginary line near the Equator, where a compass needle balances horizontally, the attraction of the north and the south magnetic poles being equal.

A series of devices, materials, and workers that allow one object after another to be assembled step-by-step.

A term applied to an overworked, inadequately staffed court that is unsympathetic and considered to be unfair to criminal defendants.

Extra radiation at certain specific wavelengths in a spectrum, compared with neighboring wavelengths (colors): An emission line is a spectral line occurring from emissions of electromagnetic radiation by atoms, ions, or molecules in the course of changes from agitated states to conditions of lower energy.

Electromagnetic radiation emitted or absorbed at discrete frequencies or wavelengths: A spectrum of line emission occurs when a hot gas gives off certain wavelengths of illumination which then produces lines on a dark background.

An inverter that is tied to a power grid or line. The commutation of power (conversion from direct current to alternating current) is controlled by the power line; so, if there is a failure in the power grid, the photovoltaic system cannot feed power into the line.

A mark indicating the general course or tendency of something; such as, a geographical feature or a set of points on a graph: The trend lines on the chart show the differences between employment and unemployment for the previous month.