Electric Circuits Science 9

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

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

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

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)

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)

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

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

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

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

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

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

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

Symbols and Diagrams

Questions Page 305 # 2-9