1. Electric Circuits
Science 9

2. Current Electricity
Refers to electric charges flowing in a circuit through a conductor in a controlled way

3. Electric Circuits
Electric circuit = continuous path for electricity to flow through
Electricity flows along a conductor from an energy source (battery) to a device that uses energy

4. Parts of an Electric Circuit
Example: Flashlight
Conductor, Energy Source, Device uses energy

5. Energy Sources of Circuits
Electrical energy can be converted into other forms of energy
Light energy (LED lights)
Heat energy (cooking devices)
Sound energy (speakers)

6. Energy Sources of Circuits
The joule (J) is the SI unit for measuring energy
Example: A light bulb in a table lamp needs about 4000 J of energy each minute that it is on.
In comparison, heating 1 liter of H20 from room temperature -> boiling = 300 kJ (300,000 Joules)

7. Where does energy come from?
Electrical energy is provided by electrons

8. Sources of Electrical Energy
Electric Cell = device that converts chemical energy into electrical energy
Two types of electrical cells:
Primary
Secondary
Both contain an electrolyte and a + and - electrode

9. Sources of Electrical Energy
Primary cells can’t be recharged
Chemical reactions irreversible
Secondary cell can be recharged
Reversible chemical reactions

10. Batteries A combination of two or more electric cells
Electric cells = one cell

11. The Load in Circuits
Load refers to any device that converts electrical energy into another form of energy
Example: Toaster (electrical energy -> heat)

12. The Pathway in a Circuit
Wires connect energy source  load
Creates controlled pathway
Most metals are good “conductors”
Used for wires

13. Symbols and Diagrams
We can simplify drawings of circuits using different symbols
You will need to become familiar with drawing circuit diagrams

14. Symbols and Diagrams

16. Questions
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