a condition of matter in which more electrons are in a high energy state than in a lower energy state, as is required for the operation of a laser.
The condition of having enough excited or high-energy states distributed in a material that a chain-reaction of stimulated emission can occur. Lasers, for example, need a constant power source that maintains population inversion in order to generate radiation continuously, since each stimulated emission reduces the population of high-energy states. See also stimulated emission.
noun, Statistics. 1. a quantity or statistical measure that, for a given population, is fixed and that is used as the value of a variable in some general distribution or frequency function to make it descriptive of that population: The mean and variance of a population are population parameters.
noun, Ecology. 1. the force exerted by a growing population upon its environment, resulting in dispersal or reduction of the population.
noun, Sociology. 1. a graph showing the distribution of a population by sex, age, etc. noun 1. a pyramid-shaped diagram illustrating the age distribution of a population: the youngest are represented by a rectangle at the base, the oldest by one at the apex
[sah-loo s paw-poo-lee soo-prey-mah leks es-toh; English sey-luh s pop-yuh-lahy-soo-pree-muh leks es-toh] /ˈsɑ lʊs ˈpɔ pʊˌli suˈpreɪ mɑ lɛks ˈɛs toʊ; English ˈseɪ ləs ˈpɒp yəˌlaɪ sʊˈpri mə lɛks ˈɛs toʊ/ Latin. 1. let the welfare of the people be the supreme law: a motto of Missouri. [wohks poh-poo-lee wohks de-ee; English voks pop-yuh-lahy voks […]