1. Circuits

2. Reviewing terms

3. Circuits need 3 basic parts: An Energy Source Load (Power demand) Wires

5. Series and Parallel Circuits In series circuits, current can only take one path. The amount of current is the same at all points in a series circuit.

6. Adding resistances in series Each resistance in a series circuit adds to the total resistance of the circuit. R total = R 1 + R 2 + R 3... Total resistance (ohms) Individual resistances (  )

7. Total resistance in a series circuit Light bulbs, resistors, motors, and heaters usually have much greater resistance than wires and batteries.

8. Voltage Voltage is the rate at which energy is drawn from a source that produces a flow of electricity in a circuit; expressed in volts

9. Series and Parallel Circuits In parallel circuits the current can take more than one path. Because there are multiple branches, the current is not the same at all points in a parallel circuit.

10. Advantages of parallel circuits Parallel circuits have two big advantages over series circuits: 1. Each device in the circuit sees the full battery voltage. 2. Each device in the circuit may be turned off independently without stopping the current flowing to other devices in the circuit.

11. Short circuit A short circuit is a parallel path in a circuit with zero or very low resistance.

12. Electric Power, AC, and DC Electricity The watt (W) is a unit of power. Power is the rate at which energy moves or is used.

13. Power in electric circuits One watt is a pretty small amount of power. In everyday use, a kilowatt is used to measure power. A kilowatt (kW) is equal to 1,000 watts.

14. Paying for electricity Electric companies charge for the number of kilowatt-hours used during a set period of time, often a month. One kilowatt-hour (kWh) means that a kilowatt of power has been used for one hour. Since power multiplied by time is energy, a kilowatt-hour is a unit of energy.

15. Alternating and direct current DC—Direct Current—produced by solar cells and chemical cells (batteries) Current only flows in one direction. One end of the battery is positive and the other end is negative.

16. Alternating and direct current AC—Alternating Current Current flows back and forth (alternates) Found in homes Generators produce AC current

17. Application: Wiring in Homes and Buildings