2 Circuit DiagramsAn electric circuit is a complete path through which charge can flow.Symbols are used to represent parts of a circuitSource of electrical energyDevices that are run by the electrical energy
3 Open Circuits Switches are places where the circuit can be opened. If the switch is open, the circuit is not a complete loop, current stopsWhen the switch is closed, the circuit will resume flowDirection of current is the direction in which positive charges flow
4 Series Circuit Charge has only one path it can flow. If one element stops functioning in a series circuit, none of the elements can operate.What are sources of resistance?
5 Parallel CircuitsAn electrical circuit with two or more paths through which charges can flow
6 Power and Energy Power is the rate of doing work Electric power is the rate at which electrical energy is converted to another form of energyUnit is watt (W)Electric PowerP(watts) = I (amps) x V (volts)
7 Practice Problems1. A clothes dryer uses about 27 amps of current from a 240-volt line. How much power does it use?P = I x V = (240V)(27A) = 6500 WA camcorder has a power rating of 2.3 watts. If the output voltage from its battery is 7.2 volts, what current does it use?I = P/V = (2.3W)/(7.2V) = 0.32AA power tool uses about 12 amps of current and has a power rating of 1440 watts. What voltage does the tool require?V = P/I = (1440 W)/(12 A) = 120 V
9 Electrical SafetyCorrect wiring, fuses, circuit breakers, insulation, and grounded plugs help make electrical energy safe to use.All wires must be able to carry max expected current“Blowing a fuse”- a wire will melt if too much current passes through it
10 A circuit breaker is a switch that will open when current is too high Grounding – the transfer of excess charge through a conductor to Earth