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Electric Circuits. Series and Parallel Circuits. Circuit Diagrams. An electric circuit is a complete path through which charge can flow Circuit diagrams use symbols to represent parts of a circuit Circuit diagrams show a source of electrical energy, and devices run by electrical energy.
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Electric Circuits Series and Parallel Circuits
Circuit Diagrams • An electric circuit is a complete path through which charge can flow • Circuit diagrams use symbols to represent parts of a circuit • Circuit diagrams show a source of electrical energy, and devices run by electrical energy
Circuit Diagrams • A circuit diagram will show one or more paths for the charge to flow • Switches are where the circuit can be open • An open circuit occurs if a switch is open then the circuit is not a complete loop and the current stops • A closed circuit is when the switch is closed and the circuit is complete
Series Circuit • A series circuit has only one path that the charge can flow • If one element in a series circuit stops working then the whole circuit will not work • Each bulb in a series circuit adds resistance and makes all of the bulbs dimmer
Parallel Circuit • A parallel circuit is when two or more paths through which the charge can flow • If one element stops working then the charge can flow along another path • This is common in houses
Power and Energy • The rate at which electrical energy is converted to another form of energy is electric power • The unit is joule per second or watt (W) • Power is often in kilowatts (kW) • Power = current x voltage or P = I x V • P(watts) = I (amps) x V (volts)
Example • An electric oven is connected to a 240 volt line and it uses 34 amps of current. What is the power used by the oven? • Current = I = 34 ampsVoltage = V = 240 voltsPower = I x V • Power = 34 amps x 240 voltsPower = 8160 watts
Electrical Safety • There are several things needed to make a house safe such as correct wiring, fuses, circuit breakers, insulation, and grounded plugs • In the US most houses have an average of 120 volts and each device increases the current • If too many devices are used it may cause a fire
Home Safety • A fuse prevents current overload in a circuit • A wire in the fuse will melt if there is too much current • This is how we “blow a fuse” • Most houses now use circuit breakers • A circuit breaker is a switch that will open when a current is too high