Post on 27-Apr-2015
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Chapter 17 Section 4
Name the 3 essential parts of a circuit
Compare series circuits with parallel circuits
Explain how fuses and circuit breakers protect your home against short circuits and overloads
An electrical circuit is like a closed pathway; always forms a loop
Electric circuit: a complete closed path through which electrical charges flow
Need 3 basic parts:Energy source (ex: battery)Wires (ex: copper wire)Load (light bulb, radio) – change electrical
energy into other forms of energy
Sometimes a circuit contains a switch
Switches open and close circuits
Made of 2 pieces of conducting material
Examples: light switch, buttons on radios, keys on calculators…
http://media-2.web.britannica.com/eb-media/42/100742-050-F50E6B5F.jpg
Loads in a circuit can be connected in different ways
There are 2 types of circuits:Series Circuit
Parallel Circuit
The difference between circuit types is the way in which the loads are connected
All parts are connected in a single loop
There is only one path for the charges to follow; charges have to flow through each part of the circuit
All loads share the same current
http://www.electronicsandyou.com/circuit/series_Circuit.jpg
With any break in the circuit, charges will stop flowing
Negative: Christmas tree lights (when 1 bulb is out they all go out)
Positive: Wiring burglar alarms (if a problem occurs somewhere in the circuit, an alarm will sound)
A circuit in which loads are connected side by side
Charges have more than one path in which they can travel
Loads do not have the same current
Each load uses the same voltage
http://www.electronicsandyou.com/circuit/parallel_circuit.jpg
Each branch of the circuit can work by itself
If one load is broken, the charges will still flow through the other branches
Wiring in your home uses parallel circuitry
TV, stereo, lights, refrigerator all operate independently
Circuits branch out from a breaker box (fuse box)
“Electrical headquarters”
Each branch receives standard voltage: 120V in the US
Circuit failure Broken wires or water can cause a short
circuitR decreases, I increases, wires heat up,
fire?Overloads
Fuses Safety feature Thin strip of metal, if it gets too hot it melts,
circuit is broken, charge stops flowing Circuit breakers
Automatically opens if current is too high Strip of metal heats up, bends, opens switchGFCI: Ground Fault Circuit Interrupter
http://www.hbbuildinganddesign.com/homereport/wp-content/uploads/2009/02/gfci_outlet.jpg
Read warning signs
Make sure insulation on cords is not worn
Do not overload circuits with too many plugs
Do not plug things in when your hands are wet
Never put objects other than a plug into an electrical outlet
If a switch is closed, charges will flow through the circuit. (T/F)
The loads in a parallel circuit do not necessarily all have the same amount of current in them. (T/F)
When a short circuit occurs, resistance is increased and current decreases. (T/F)