Pathfinders
How can 1 wire, 1 battery, and 1 bulb be used to
make a complete circuit?
What about 2 wires, 1 battery, and 1 bulb?
Circuit Diagram
For the device to work, the electrical energy must flow in
a complete or closed circuit.
Basic Circuits
Basic circuits require the following components:
• An energy source (electricity or a dry cell)
• A conductor (usually a wire or something made of metal)
• A device to operate (resistor)
Would This Work?
Would This Work?
Would This Work?
Would This Work?
Would This Work?
The Central Concept: Closed Circuit
Open and Closed (Complete) Circuits
Closed Circuit
Complete Circuit
Open Circuit
Switches
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Series Circuits (L)
Connect 1 bulb to your batteries
• Draw a diagram and write one sentence describing
what happened.
Connect a total of 2 bulbs to your batteries
• Draw a diagram and write one sentence describing
what happened.
Connect a total of 3 bulbs to your batteries
• Draw a diagram and write one sentence describing
what happened.
Stop and Think
What happened as you added more bulbs to your
series circuit?
Why do you suppose that is?
How many paths does the electrical current have
to flow through?
Removing a Bulb
What do you think would happen if we removed a
bulb from a series circuit?
1. Set up a series circuit with 1 bulb.
2. Now, come and pick up a bulb holder with the
bulb removed.
3. What happened to the other bulb?
4. Why?
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Series Circuits (R)
•
Series circuits have one and only one path for an
electrical current to flow through.
•
The current flows through every part of the circuit.
In a complete series circuit, the more bulbs or devices
that are added, the ____________________________
____________________________________________.
If one bulb is removed, then _____________________
____________________________________________.
Series Circuit Examples
Toys that use batteries
Cell Phones
Computers and Tablets
Blenders
Televisions
Holiday Lights (old fashioned)
Any others??
Making Parallel Circuits
Make a series circuit with 1 bulb
• Draw a diagram and write one sentence describing
what happened.
Parallel Circuits (L)
Make a series circuit with 1 bulb.
Next, connect a total of 2 bulbs to your battery like this:
• Draw a diagram and write one sentence describing
what happened.
Parallel Circuits (L)
Now add a third bulb in your parallel circuit like this:
• Draw a diagram and write one sentence describing
what happened.
Stop and Think
What happened as you added more bulbs to your
parallel circuit?
Why do you suppose that is?
How many paths does the electrical current have
to flow through?
Removing a Bulb
What do you think would happen if we removed a
bulb from a parallel circuit?
1. Set up a parallel circuit with 2 bulbs.
2. Now, come and pick up a bulb holder with the
bulb removed. Swap it out with one of the
bulbs in your parallel circuit.
3. What happened to the other bulb?
4. Why?
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Parallel Circuits (R)
•
Parallel circuits have more than one path for an
electrical current to flow through.
•
Have at least one point where the current divides or
splits into different branches.
In a complete parallel circuit, the more bulbs or devices
that are added, the ________________________________
________________________________________________.
If one bulb is removed, then _________________________
________________________________________________.
Parallel Circuit Examples
School and business lighting and outlets
Household lighting and outlets
Electrical wiring in cars
Microwave
Refrigerator
Holiday lighting (newer strands)
Any others??
Lights in a Series Circuit
Lights in a Parallel Circuit
Series and Parallel Circuits
Batteries in Series & Parallel
Comparison
Series Circuit
Parallel Circuit
Only one path for
Definition current to flow
Multiple paths for
current to flow
Total resistance
Resistance
increases
Total resistance
stays same
-Holiday lights
Examples
(traditional)
-Household
Current