1. Electric Circuits Series and Parallel Circuits

2. 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

3. 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

4. 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

5. 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

6. 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)

7. 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 amps Voltage = V = 240 volts Power = I x V Power = 34 amps x 240 volts Power = 8160 watts

8. 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

9. 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