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…

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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

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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

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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

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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)