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Lesson

Component and Schematic Terminology

The following table summarizes the information that you need on components in order to work with circuit diagrams

Component	Schematic Symbol	Function	Letter	Unit of Measure
Conductor		A wire or other device that conducts electricity to components
Battery		Supplies DC current		Volts (V)
DC power supply		Supplies DC current		Volts (V)
AC power supply		Supplies AC current		Volts (V)
Resistor		A device that restricts the flow of current	R	Ohm () (Greek letter omega)
Variable Resistor		Restricts the flow of current. Can be adjusted (rotary or slider)	R	Ohm ()
Light Dependant Resistor		A transducer that converts light energy to electrical resistance. More light means less resistance	LDR	Ohm ()
Thermistor (temperature dependant resistor)		A transducer that converts thermal energy (heat) to electrical resistance. More heat means less resistance.		Ohm ()
Light bulb		A transducer that converts electrical energy into light
Diode		Allows current to flow only in one direction
Zener Diode		A diode that allows current to flow only at a fixed voltage
LED (Light Emitting Diode)		A transducer that converts electrical energy into light energy
Inductor (Coil)		A coil of wire that creates an electromagnetic field when current flows. If a moveable iron core is added, it becomes a transducer that converts electrical energy into motion.	L	henry (H)
Transformer		Two coils with an iron core. Electrical energy is transferred from one to the other through the electromagnetic field. They can step the voltage up or down.	L	henry (H)
NPN Transistor		A device that can use small currents to control large currents. Can be a switch or an amplifier	T
PNP Transistor		A device that can use small currents to control large currents. Can be a switch or an amplifier	T
Phototransistor		A transistor that is light sensitive. The light turns the transistor on and off	T
Capacitor		A device that stores electrons (electrical charge) on conductive plates separated by an insulator. Blocks DC current and passes AC current.	C	farad (F)
Electrolytic Capacitor		A capacitor that has to be connected right-way around (polarized)	C	farad (F)
Variable Capacitor		A variable capacitor	C	farad (F)
On-Off Switch		Turns current on and off	S
Two-way Switch		Allows switching between two parts of a circuit
Volt Meter		Measures electromotive force (volts)
Ammeter		Measures electrical current (amperes, or amps)
Ohmmeter		Measures electrical resistance (ohms)

Units and Multipliers

Units of measure in electricity may be measured in very large or very small quantities. Multipliers are used with units to handle these smaller and larger quantities.

Activity

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