Page 100 - The Ontario Curriculum, Grades 9 and 10: Science, 2008 (revised)

THE ONTARIO CURRICULUM, GRADES 9 AND 10 | science
dilute. A substance that has a relatively low con- centration of solute. A dilute solution is created by modifying or adding a substance to a solution.
direct current (DC). An electric current in which the net flow of charged particles travels in one direction only.
displacement reaction (single). A reaction in which one element in a compound replaces another element in a compound.
disturbed ecosystem. An ecosystem that has been altered by human activity.
diverging (concave) lens. A lens that is thinnest in the middle, causing parallel rays of light to diverge.
diverging (convex) mirror. A mirror that curves outward, causing parallel rays to spread farther apart from a principal focal point.
diversity. An abundance of variety in the plant and animal communities and species within a given area.
ecosystem. A complex, self-regulating system through which energy and materials are trans- ferred, made up of a group of living organisms and their abiotic environment, which interact as a unit.
efficiency. The amount of useful energy pro- duction achieved in relation to the amount of energy supplied.
electric charge. Positively or negatively charged particles that exert an electric force.
electric current. A measure of the number of charged particles that pass by a point in an elec- trical circuit each second.
electric discharge. The very quick transfer of an electric charge.
electrical circuit. A circular path for electron flow, including a source, a load, and conducting wires.
electrical energy consumption. The amount of electrical energy used, usually measured in kilowatt-hours.
electrical load. A device that uses electrical energy in a circuit.
electrical source. A source of electrical energy that creates potential difference in a circuit (e.g., a battery, an electrical outlet).
electromagnetic radiation. Radiation consist- ing of electromagnetic waves that travel at the speed of light (e.g., visible light, radio waves, gamma rays, X-rays).
electromagnetic spectrum. The entire range of wavelengths or frequencies of electromagnetic radiation, extending from gamma rays to the longest radio waves, including visible light.
electron. A small, negatively charged particle that travels in an orbit around the nucleus of an atom and acts as the particle of electricity in solids.
electrostatics. The study of electric charges at rest.
element. A pure substance that cannot be bro- ken down into simpler substances (e.g., iron, sulfur, oxygen).
environment. All the biotic and abiotic elements that surround and affect organisms or groups of organisms and influence their survival and development.
equilibrium. A state in which opposing forces or actions are balanced. Equilibrium may be either static or dynamic.
extrapolate. To infer values by extending or projecting known information (e.g., to draw conclusions about the future from observed trends in a graph).
fluorescence. A light emitted during exposure of the source to electromagnetic radiation.
focal length. The distance from the vertex to the principal focus of a curved mirror.
9