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Physics 11 Glossary

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Glossary A bitumen: a mixture of hydrocarbons and other substances that occurs naturally or is obtained by distillation from coal or accelerated motion: nonuniform motion that involves change petroleum in an object’s speed or direction or both acceleration: rate of change of velocity C acceleration due to gravity: the vector quantity 9.8 m/s2 [down], represented by the symbol g៬ cataract: opaque, cloudy area that develops in a normally clear eye lens acoustics: the total effect of sound produced in an enclosed space charge coupled device: (CCD) a light-sensitive device used to store data active solar heating: the process of absorbing the Sun’s energy and converting it into other forms of energy chromatic aberration: coloured fringes around objects viewed through lenses alternating current: (AC) results when charges periodically reverse direction circuit: a path for electric current ammeter: a device that measures the amount of electric cur- closed air column: column closed at one end and open at the rent in a circuit other ampere: (A) the SI unit of electric current, 1 A = 1 C/s coefficient of friction: ratio of the magnitude of friction to the magnitude of the normal force amplitude: distance from the equilibrium position to max- imum displacement coefficient of kinetic friction: ratio of the magnitude of kinetic friction to the magnitude of the normal force angle of incidence: (vi) the angle between the incident ray and the normal coefficient of static friction: ratio of the magnitude of the maximum static friction to the magnitude of the normal force angle of reflection: (vr) the angle between the reflected ray and the normal cogeneration: the process of producing electricity and using the resulting thermal energy for heat angle of refraction: (vR) the angle between the refracted ray and the normal compression: region in a longitudinal wave where the particles are closer together than normal antinode: point midway between the nodes where maximum constructive interference occurs conduction: the process of transferring heat through a material by the collision of atoms arc: light produced by air molecules when a current jumps a gap in an electric circuit conductor: solid in which charge flows freely armature: a pivoted bar of soft iron consonance: combinations of sounds of specific frequencies that are pleasing to the ear; the frequencies are often in a astigmatism: eye defect in which the cornea or the lens of the simple ratio eye is not perfectly spherical constructive interference: occurs when waves build each other atmosphere: the air in a specific place that can be used as a up, resulting in the medium having a larger amplitude source of heat convection: the process of transferring heat by a circulating atom: sub-microscopic particle of which all matter is made path of fluid particles average acceleration: change of velocity divided by the time conventional current or electric current: describes electric interval for that change charges travelling through a conductor from the positive ter- average speed: total distance of travel divided by total time of minal to the negative terminal of the source of electric potential travel converging lens: lens that causes parallel light rays to come average velocity: change of position divided by the time together so that they cross at a single focal point interval for that change coulomb: (C) the SI unit of electric charge Coulomb’s Law: The magnitude of the force between two B charged objects is directly proportional to the product of the base unit: unit from which other units are derived or made up charges and inversely proportional to the square of the distance between them. beat frequency: the number of beats heard per second in hertz crest or positive pulse: high section of a wave beats: periodic changes in sound intensity caused by interfer- ence between two nearly identical sound waves critical angle: (vc) the angle in an optically denser medium at which total internal reflection occurs; at this angle the angle of biomass energy: the chemical potential energy stored in plants refraction in the less dense medium is 90° and animal wastes cycle: one complete vibration or oscillation 582 Glossary D electric potential difference: (V ) the amount of work required per unit charge to move a positive charge from one point to decibel: (dB) unit used to measure sound intensity level another in the presence of an electric field (0 dB = 10–12 W/m2) electromagnet: object that exerts a magnetic force using elec- derived unit: unit that can be stated in terms of the seven base tricity units electromagnetic force: force caused by electric charges destructive interference: occurs when waves diminish one electron: negatively charged particle which moves around the another and the amplitude of the medium is less than it would nucleus of an atom have been for either of the interfering waves acting alone electron flow: a term used to indicate that the electric current diamagnetic: materials that cause a very slight decrease in the in metals is due to the motion of electrons magnetic field of a coil electroscope: device that is used to detect the presence of an diffraction: the bending effect on a wave’s direction as it passes electric charge and to determine the charge’s “sign” (that is, through an opening or by an obstacle whether it is positive or negative) digital camera: camera that uses digital information instead of electrostatic series: chart that shows a substance’s tendency to film to capture images gain or lose electrons dipoles: atoms of ferromagnetic substances that act like tiny elementary charge: (e) electric charge of magnitude equal to magnets the charge on a proton and an electron direct current: (DC) results when charges flow in a particular elements: the components of an electric circuit direction energy: the capacity to do work dispersion: the spreading of white light into a spectrum of colours energy resource: raw material obtained from nature that can be used to do work displacement: change in position of an object in a given direction energy transformation: the change from one form of energy to another dissonance: combinations of sounds of specific frequencies that have a harsh effect; the frequencies are not in a simple energy transformation technology or energy converter: a ratio system that converts energy from some source into a usable form diverging lens: lens that causes parallel light rays to spread equivalent resistor: resistor that has the same current and apart so that they appear to emerge from the virtual focal point potential difference as the resistors it replaces Doppler effect: when a source of sound approaches an observer, the observed frequency increases; when the source F moves away from an observer, the observed frequency ferromagnetic: a substance that can become magnetized decreases first law of motion: If the net force acting on an object is zero, doubling time: the time required for an amount to double the object will maintain its state of rest or constant velocity. dynamics: the study of the causes of motion fixed-end reflection: reflection from a rigid obstacle when a pulse is inverted E focal length: (f ) the distance between the principal focus and echo: reflected sound waves the optical centre, measured along the principal axis echolocation: location of objects through the analysis of focal plane: the plane, perpendicular to the principal axis, on reflected sound. which all focal points lie eddy currents: induced currents that form closed loops within focal point: (waves) a specific place where straight waves are a conductor reflected to; (optics) the position where parallel incident rays meet, or appear to come from, after they pass through a lens efficiency: the ratio of the useful energy provided by a device to the energy required to operate the device force: a push or a pull electric charge: a basic property of matter described as nega- force field: space surrounding an object in which the object tive or positive exerts a force on other objects placed in the space electric field: the space around a charged object where forces frame of reference: coordinate system relative to which a of attraction or repulsion act on other objects motion can be observed electric generator: a device that converts the mechanical free-body diagram: (FBD) drawing in which only the object energy of motion into electrical energy being analyzed is drawn, with arrows showing all the forces acting on the object Glossary 583 free-end reflection: reflection where the new medium is free to I move and there is no inversion ᎏnumber ᎏof cycles image point: point at which light from an object point converges frequency: (f ) the number of cycles per second f = total time incident ray: the approaching ray of light friction: force between objects in contact and parallel to con- tact surfaces index of refraction: (n) the ratio of the speed of light in a vacuum (c) to the speed of light in a given material (v); n = ᎏcᎏ f-stop number: the ratio of the focal length of the lens to the v ᎏfᎏ induced charge separation: distribution of charge that results diameter of the aperture; f-stop = d from a change in the position of electrons in an object fuel cell: device that changes chemical potential energy directly into electrical energy induced field: the magnetic field produced by the induced current fundamental forces: forces are classified into four categories— gravitational, electromagnetic, strong nuclear, and weak inducing field: the magnetic field that causes the induced nuclear current inertia: the property of matter that causes a body to resist fundamental frequency: (f0) the lowest natural frequency changes in its state of motion fundamental laws of electric charges: Opposite charges attract each other.
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