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Current and Circuits. Circuits Schematics Use of Meters. Objectives. Describe the utilization of ammeters and voltmeters in circuits. Describe the utilization of fuses and circuit breakers in protecting electrical circuits. Circuit Defined.
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Current and Circuits Circuits Schematics Use of Meters
Objectives • Describe the utilization of ammeters and voltmeters in circuits. • Describe the utilization of fuses and circuit breakers in protecting electrical circuits
Circuit Defined • A circuit is a path for electrons to flow through. The path is from a power source’s negative terminal, through the various components and on to the positive terminal • Types • Series • Parallel • Combination
- + Components - Source DRY CELL a source of electrical energy
Components - Load LIGHT BULB lights up when electricity pass through
- + Circuit - Complete Source of electrical energy Appliances Complete circuit Electricity flows
Terms to Know • Open circuit – there is a break somewhere and electricity cannot flow (maybe the switch is open) • Closed circuit – electricity can flow (the switch is closed) • Short circuit – the electricity completes a circuit without going through the load • Load – what is using the electricity
Schematics Circuit diagrams, also called schematic diagrams, provide a graphic representation of an electric circuit using standard symbols.
Diagram Symbols wire or conductor resistor or other load bulb voltmeter battery ammeter switch generator V A
The Ammeter • This device measures current. • It is a Galvanometer wired in parallel to a resister (shunt). • Ammeters are connected in series to the circuit.
The Voltmeter • This device measures electric potential…voltage. • It is a Galvanometer wired in series with a resistor (a multiplier.) • Voltmeters are connected in parallel to the load
Circuit Breaker Fuses Fuses and Shorts • Too many devices can require more current than the wires can handle -- overheating of wires is a fire hazard !!! If an electric circuit gets “overlo aded” (too much current!) fuses or circuit breakers interrupt the flow of current.
- + A + - A Example – Simple Circuit circuit diagram
- + A + - A Complex Circuit Construct the circuit diagram