Ch. 20 - Electricity Section 20.1 Electric Charge and Static Electricity p. 600

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<ul><li><p>Ch. 20 - ElectricitySection 20.1Electric Charge and Static Electricityp. 600</p></li><li><p>Electric ChargeCauses subatomic particles to attract/repel2 types+ and Everything affected by charge</p></li><li><p>Neutral atom = protons &amp; e-sGain e-s = - ion Lose e-s = + ionExcess/shortage of e-s produce net chargeCoulomb (C) - SI unit of electric charge 6.24 x 1018 e-s = 1 C</p></li><li><p>Electric ForcesOpposite charges attractElectric force depends on charge &amp; distance2x distance = electric forceStronger than gravityHold atoms together</p></li><li><p>Electric FieldsThe effect electric charge has on other chargesStrength depends on amt of charge producing field &amp; distance from chargeExerts forces on charged object placed in field.More net charge object has, greater force on it</p></li><li><p>Static Electricity and ChargingStatic Electricitynet accumulation of electric charges on an objectCharge can be transferred byFrictionContactInduction</p></li><li><p>Static Electricity and ChargingDuring charge transfer, total charge same before &amp; after transferLaw of conservation of charge</p></li><li><p>Charging by frictione-s move from hair to balloonAtoms in rubber &gt;attraction for e-sBalloon net chargeHair net + charge - -+ + +</p></li><li><p>Charging by contactTouch electrically charged object you become chargedSphere still has net charge, but reducedVan de Graaff generator</p></li><li><p>Charging by InductionTransfer of charge w/o contact btwn materialsWalk across carpetPick up extra e-s; net chargeRepels e-s in doorknobLeaves net + charge on doorknob closest to handDoorknob overall charge neutral, but charges moved within it</p></li><li><p>Static DischargeOccurs when pathway forms for charges to moveAir becomes charged when hand near doorknobAir provides path for e-s</p></li><li><p>Static Discharge lightningCharge built up from friction btwn moving air masses in clouds- charge in bottom of cloud induces + charge in groundCharge in cloud increasesAttraction increasesAir charged pathway for e-s Lightning 5:06</p></li><li><p>Chapter 20.2Electric Current and Ohms Lawp. 604</p></li><li><p>Electric CurrentContinuous flow of electric chargeSI unit is ampere, or amp (A)2 types:Direct current (DC)Alternating current (AC)</p></li><li><p>Direct CurrentCharge flows in 1 directionMost battery opperated devicesFlashlightsRemotes</p></li><li><p>Alternating CurrentCurrent that regularly reverses its directionElectric current in homes, businesses, &amp; schools often use AC</p></li><li><p>Electric current in a flashlighte-s flow from - to + terminalCurrent in opposite direction!Scientists define current as direction + charges flow</p></li><li><p>Conductorsmaterial that allows e-s to flow easilyMetals like copper and silverMade of ions in a latticeions - atoms that gained or lost e-sIons not free to moveEach ion has e-s loosely held Free e-s conduct charge</p></li><li><p>Insulatorsmaterial that doesnt allow e-s to move through it easilye- are tightly heldex: plastic, wood, rubber, glass</p></li><li><p>Resistancee-s in electric curent collideopposes flow of e-selectrical energy converted to thermal energy &amp; lightmeasured in ohms ()Thickness, length, temp affect resistance</p></li><li><p>Resistance depends on..wire thicknessmore resistance in thinner wiresmilkshake in thin v.s. thick strawwire length more resistance in longer wiresTemphigh resistance at high tempse-s collide more often</p></li><li><p>Superconductors</p><p>Can resistance ever be 0?Superconductors produce near zero resistance when cooled to low temps.</p></li><li><p>VoltagePotential Difference (voltage)diff in electrical potential btwn 2 places in electric fieldSimilar to PE diff of water at top and bottom of fountainlarge separation of charge creates high voltageLarge fountain high PEpush causing e- to move from - to +measured volts (V)</p></li><li><p>Voltage sourcesFountains pump water to top, voltage source increases PE of electric chargesbatteriessolar cellsgenerators</p></li><li><p>Ohms Lawincreasing voltage increases currentIncreasing resistance decreases current</p></li><li><p>A lightbulb with a resistance of 160 is plugged into a 120-V outlet. What is the current flowing through the bulb?</p><p>GIVEN:R = 160 V = 120 VI = ?</p></li><li><p>ElectroscopeElectroscopeinstrument that detects presence of electrical chargesleaves separate when they gain + or - charge</p><p>11</p></li></ul>


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