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solar energy

(Encyclopedia)solar energy, any form of energy radiated by the sun, including light, radio waves, and X rays, although the term usually refers to the visible light of the sun. Solar energy is needed by green plants...

Brown v. Board of Education of Topeka, Kans.

(Encyclopedia)Brown v. Board of Education of Topeka, Kans., case decided by the U.S. Supreme Court in 1954. Linda Brown was denied admission to her local elementary school in Topeka because she was black. When, com...

photoelectric cell

(Encyclopedia)CE5 Photoelectric cell: Light causes a photosensitive surface to emit electrons, which flow as current to the positive terminal. A galvanometer measures the current and thus indicates light intensi...

blast furnace

(Encyclopedia)CE5 Blast furnace for production of iron blast furnace, structure used chiefly in smelting. The principle involved in this means of extracting metals is that of the reduction of the ores by the ac...

mechanics

(Encyclopedia)mechanics, branch of physics concerned with motion and the forces that tend to cause it; it includes study of the mechanical properties of matter, such as density, elasticity, and viscosity. Mechanics...

magic, in religion and superstition

(Encyclopedia)magic, in religion and superstition, the practice of manipulating and controlling the course of nature by preternatural means. Magic is based upon the belief that the universe is populated by unseen f...

mass, in physics

(Encyclopedia)mass, in physics, the quantity of matter in a body regardless of its volume or of any forces acting on it. The term should not be confused with weight, which is the measure of the force of gravity (se...

Santa Anna, Antonio López de

(Encyclopedia)Santa Anna, Antonio López de äntōˈnyō lōˈpās dā sänˈtä äˈnä [key], 1794–1876, Mexican general and politician. He fought in the royalist army, but later joined Iturbide in the struggle...

recognition

(Encyclopedia)recognition, acknowledgment of the admission of new states into the international community by political action of states that are already members. Its derivation is found in the policy of the older E...

Navigation Acts

(Encyclopedia)Navigation Acts, in English history, name given to certain parliamentary legislation, more properly called the British Acts of Trade. The acts were an outgrowth of mercantilism, and followed principle...