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Electricity and Electronics Brad Dearing 108 University High School Normal, IL 61761 (309) 438-5513 [email protected] The Nature of Matter • Matter – anything that has mass and takes up space. – Element – the most basic form of a substance.(Sodium) or (Chlorine) • Compound – the combination of two or more elements. (Salt) • Molecule – the smallest part of a compound that still retains its unique properties. (One small piece of salt) – Atom – smallest part of an element (one sodium atom) • Electrons – Negative part of atom (11 electrons in Na) • Protons – Positive part of atom (11 protons in Na) • Neutrons – No charge or neutral part of atom (11.990 neutrons in Na) Ionization • Ionization occurs when an atom gains or loses an electron. – Positive Ion – more protons than electrons in an atom (loses an electron) – Negative Ion – more electrons than protons in an atom (gains an electron) Static Electricity • • • • Electricity at rest (static) Stationary charge Produced by friction Law of charges: Like charges repel each other and unlike charges attract each other. Terms • Coulomb – the measurement of the amount of electricity. 1 coulomb = 6.24 x 1018 electrons • Electrostatic Fields – the field of force surrounding a charged body. (dielectric field) See next slide • Induction – the transfer of a charge without direct contact, bringing it close to another object. Basic Electrical Circuit • Source of voltage (battery) • Load (lamp) • Conductors (wires) Polarity Terms • Battery – form of DC electricity, generally by chemical reaction. • Load – when electrical energy is converted to some other form of energy. (i.e. light, heat, magnetism, etc.) • Conductor – pathway conducive to carrying electricity, generally coated with a protective coating. Terms • Voltage – the force behind electron flow. (volts: V) aka: potential, potential difference, or electromotive force (emf) (E) • Current – the flow of electrons. (ampere: A) (I) 1 amp = 1 coulomb of charge flowing past a point in one second. • Resistance – the opposition to the flow of electrons. (ohms: ) Terms • Conductor – anything that permits the free flow of electrons. • Insulator – extremely poor conductors. • Semiconductor – a material that limits the flow of electrons, considered neither a good conductor nor a poor conductor. See table of common conductors and insulators p. 27 Current • AC – Alternating Current: flows in both directions. (household current) (Cycle or hertz: Hz) • DC – Direct Current: flows in only one direction in a circuit. (battery) Electron Flow Theory • Conventional current flow theory – positive to negative. • Electron flow theory – negative to positive. Series and Parallel voltage Ohm’s Law E=IxR I=E/R R=E/I current resistance