1. Chapter 16:Electricity
Section 3 – Circuits

2. Circuits
Definition: circuit – a set of components that allow one or more complete paths for electric current to flow.
Any time electricity is flowing, a circuit is present.

3. Circuits
When electricity is able to flow freely through a circuit, that circuit “closed”.
Incomplete circuits will not allow electricity to flow freely.
They are called “open” circuits.

4. Circuit Components Circuits consist of many different things.
The most common components of a circuit are:
Power Supplies
Wires
Resistors
Bulbs
Switches
Definition: resistor – a device that blocks SOME (not all) electric current in a circuit.
Appliances like TV’s, lights, computers…these are all resistors.

5. Basic Circuit Symbols (copy these to notes!)
Resistor
Wire
Battery or
Power Source
Bulb
Open Switch
Closed Switch

6. Types of Circuits
Definition: series circuit – a circuit that forms a single pathway.
Electricity can only flow one way in a series circuit.

7. Types of Circuits
Definition: parallel circuit – a circuit that forms multiple pathways for electricity.
Parallel circuits can have a piece removed from them and still allow electricity to flow in another part of the circuit.

9. Electric Current in wires….
Electric resistance explains why electronics get hot as they run.
Even conductors cause some resistance.
As a wire gets thicker, there is less resistance.
Lots of Resistance
Some Resistance
Little resistance

10. Electric Current in wires….
As a wire gets shorter, there is less resistance.
Lots of Resistance
Some Resistance
Little resistance

11. Electric Current in wires….
As a wire gets thicker it can carry more electric current.