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Electricity and Electrical Circuits
Chapter SectionsO 1 - Electrical Circuits
O 2 - Current and Voltage
O 3 - Resistance and Ohm’s Law
1 - Electrical Circuits
Electrical CurrentO The flow of electricity through wires,
motors, light bulbs, and other devices
O Typically the flow of electrons
O Very dangerous – your nerves use electricity to function
Electrical CircuitsO A complete path through which
electricity travels
O Wires in circuits are like pipes that carry water
Electrical SymbolsO Circuit diagrams use
symbols to make drawing circuits simpler and easier
Open and Closed Circuits
O Open circuit has a break which stops the flow of electricity
O Closed circuit has no breaks
O Switches and Circuit Breakers open and close a circuit
2 - Current and Voltage
CurrentO Current is measured in
amperes (A)
O Current flows from positive to negative
O Current is the flow or motion of charges
Measuring currentO Measured with an
ammeter
O The current must pass through the meter
O Can be either AC or DC, which we will learn about in Chapter 14
VoltageO Measured in volts (V)
O Measures electrical potential energy
O A higher potential difference (more volts) means that more work can be done
Measuring VoltageO Measured with a volt meter
O A multimeter can measure voltage, current, and resistance
BatteriesO Use chemical energy
to create voltage.
3 - Resistance and Ohm’s Law
ResistanceO The measure of how
strongly a wire or other object resists current flowing through it
Measuring ResistanceO Measured in ohms (Ω = omega)
Ohm’s Law
Using Ohm’s Law
Conductors and Insulators
O Electricity flows easily through conductors
O Electricity is blocked by insulators
O Materials in between these two are called semiconductors
PotentiometersO A potentiometer is a
variable resistor that is used to control the flow of current
O Dimmer switches and volume controls are examples