1. Topic: Electrical Circuits PSSA: 3.4.7.B / S8.C.2.1

2. Objective:  TLW identify three essential parts of an electrical circuit.  TLW compare series circuits with parallel circuits and evaluate the benefits of each.  TLW explain the purpose of circuit breakers and fuses in home electrical systems.

3. MI #1: What is an Electrical Circuit?  An electrical circuit is a complete closed path through which electricity flows.  There are 3 parts to a circuit… 1. Energy Source 2. Wire 3. Load

4. MI #2: Switches  A switch is a device that is used to open and close a circuit.  If the circuit is open, electricity cannot flow so the load is not using energy.  If the circuit is closed, electricity is flowing through the circuit.

5. MI #3: Series Circuits  A series circuit is a circuit in which all parts are connected in a single loop.  There is only one path for the electricity to follow; all loads in the series share the same current.  If there is any break in the circuit, the charge stops flowing.  Series circuits are useful for burglar alarms, cheap Christmas lights, etc.

6. MI #4: Parallel Circuit  A parallel circuit is a circuit in which loads are connected side by side, therefore, the current has more than one path that it can follow.  Home wiring systems use parallel circuits because if one load fails, the charge can still run through the other loads.

7. MI #5: Household Circuit Safety  Circuits may fail if a wire breaks, water gets into the electrical system, or if they are overloaded.  Fuses open a circuit if the current is too high, preventing overload; fuses must be replaced if they trip.  Circuit breakers act like fuses, except they are able to be closed again if tripped.

8. MI #6: Electrical Safety Tips  Make sure insulation on cords is not worn.  Do not overload circuits by plugging in too many electrical devices.  Do not use electrical devices near water.  Never put objects other than a plug in an electrical outlet.

9. So What…? Real Life Application  Understanding how circuits work is important in understanding household electrical systems.