| Glossary | ||||||||||||||
| chain reaction
— chemical or nuclear reaction where the products of one reaction can create more than one additional reaction.
A nuclear chain reaction is at the heart of nuclear fission. Charles’s law — for a gas at constant pressure, the change in volume is directly proportional to the change in absolute temperature. Often written as V1/T1 = V2/T2. circuit breaker — safety device in a circuit that stops the flow of current when a maximum current is exceeded. A circuit breaker can be reset manually after the current is brought below the maximum allowed value. closed circuit — electric circuit where the switch is connected (or closed), allowing electricity to flow through the circuit. The opposite of an open circuit. closed system — isolated system that cannot exchange matter or energy with its surroundings. coefficient of kinetic friction — ratio of the force of dry sliding friction between moving surfaces divided by the normal force acting between the surfaces. coefficient of rolling friction — ratio of the force of dry sliding friction between moving surfaces divided by the normal force acting between the surfaces. coefficient of static friction — ratio of the maximum force of static friction between two stationary surfaces divided by the normal force acting between the surfaces. collision — interaction that causes one or more objects to change their velocity. commutator — device attached to the armature of a motor (or generator) that provides an electrical connection and allows the direction of current to be changed periodically during the rotation of the motor. In an electric motor, the commutator plates typically comes in electrical contact with the brushes. compass — instrument that indicates direction relative to the north–south and east–west axes, usually based on sensing Earth’s magnetic field. | component
— (1) part of a vector; (2) projection of a vector against one of the coordinate axes. component force — force that lies along one of the three coordinate axes (x, y, or z). compound machine — machine consisting of two or more simple machines. compressible — fluid that significantly changes its volume in proportion to changes in pressure. concave — curved form, usually for a mirror or lens, that is depressed inwards in its middle. concave lens — diverging lens that is thinner in its middle than at its outer part. A concave lens produces a virtual and upright image that is reduced in size. cones — light-sensitive cells in the eye that respond to color. constructive interference — occurs when two or more waves, of the same phase, add together to create a larger wave. continuum spectrum — spectrum apparently containing all wavelengths of light over a broad range in wavelength. Also called a continuous spectrum. control rods — rods made of a material that absorbs neutrons. They are used to control the rate of nuclear reactions occurring in a nuclear reactor. convection — transfer of heat through the motion of matter, such as blowing hot air or circulating a liquid coolant. conversion factor — ratio used to transform a quantity expressed in one unit (or set of units) into another unit (or set of units). In a conversion factor, the same quantity appears in both the numerator and denominator but is expressed in two different units. A conversion factor has a value of exactly one. Example: the conversion factor from centimeters to meters is (1 m/100 cm). convex — curved form, usually for a mirror or lens, that bulges out in the middle. convex lens — converging lens that is thicker in its middle than at its outer part. If the object is located outside the focal point, then the image is inverted and real. If the object is located inside the focal point, then the lens becomes a magnifying glass producing a virtual and upright image. | |||||||||||||
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