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Electricity. Physical Science Chapter 16. Electricity Basics. Electricity is caused by the flow (or net movement) of Electrons Electric Current – the rate that positive charges flow in a circuit Actually a measure of the rate that negatively charged electrons move
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Electricity Physical Science Chapter 16
Electricity Basics • Electricity is caused by the flow (or net movement) of Electrons • Electric Current – the rate that positive charges flow in a circuit • Actually a measure of the rate that negatively charged electrons move • Electrons Will Move From Higher To Lower Potential
Electric Current • Measured in Amperes (A) • Ampere = 1 Coulomb of charge per second • Voltage or Potential Difference – measure of potential energy (in Joules) • Voltage occurs across the two terminals of a battery and range from 1.5 V for a small battery to 12 V for a car battery • Voltage sets charge in motion • Electrons move from the negative terminal to the positive terminal
Resistance • Resistors oppose the rate of charge flow in the circuit • Caused by internal friction • The resistance of the filament of a light bulb determines how bright the bulb is • Example: 4o Watt bulb has a higher resistance than a 100 Watt bulb • Resistance = Voltage / Current • Unit - Ohms
Conductors vs. Insulators • Conductors – allow electrons to flow easily • Contain a lot of free electrons • Offer Little Resistance To Current Flow • Good Conductors • Metals (copper, gold, silver, aluminum) • Electrolyte Solutions • Insulators – do not allow electrons to flow easily or at all • Contain Few Free Electrons • Insulator Materials • Air, Wood, Glass
Relationship of Current to Potential Difference • As Current Increases – Potential Difference (Volts) Increase • As Current Increases – Resistance Decreases
Circuits • Circuit – bulb, battery, and wires • Closed Circuit – completed path – electricity flows • Open Circuit – not a complete path – no current • Parallel Circuit – multiple path for a circuit • Series Circuit – one path for a circuit