What electrical component opposes the flow of current in a DC circuit?
AnswerResistor
A resistor limits current by opposing the flow of electric charge. In a DC circuit, that opposition is called resistance.
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T6 · Electronic Components
Technician · correct answers only, in question-pool order.
What type of component is often used as an adjustable volume control?
AnswerPotentiometer
A potentiometer is a variable resistor with an adjustable contact. Audio volume controls commonly use it to vary the signal level.
What electrical parameter is controlled by a potentiometer?
AnswerResistance
A potentiometer changes resistance as its shaft or slider moves. That variable resistance is what lets it control things such as audio level.
What electrical component stores energy in an electric field?
AnswerCapacitor
A capacitor stores separated electric charge on conductive plates, creating an electric field between them.
What type of electrical component consists of conductive surfaces separated by an insulator?
AnswerCapacitor
A capacitor is fundamentally two conductive surfaces separated by an insulating material called a dielectric.
What type of electrical component stores energy in a magnetic field?
AnswerInductor
An inductor stores energy in the magnetic field produced by current flowing through it.
What electrical component is typically constructed as a coil of wire?
AnswerInductor
An inductor is commonly made by winding wire into a coil. The coil concentrates the magnetic field created by current.
What is the function of an SPDT switch?
AnswerA single circuit is switched between one of two other circuits
SPDT means single-pole, double-throw. One common connection is switched between either of two other contacts.
What type of switch is represented by component 3 in figure T-2?
AnswerSingle-pole single-throw
In figure T-2, component 3 is the symbol for a single-pole single-throw switch: one pole that simply opens or closes one circuit.
Which of the following battery chemistries is rechargeable?
AnswerNickel-metal hydride, lithium-ion, and lead-acid.
Nickel-metal hydride, lithium-ion, and lead-acid batteries are all rechargeable chemistries when charged with the proper method for that battery type.
Which of the following battery chemistries is not rechargeable?
AnswerCarbon-zinc
Ordinary carbon-zinc cells are primary batteries intended for one-time use rather than routine recharging.
Which is true about forward voltage drop in a diode?
AnswerIt is lower in some diode types than in others
Different diode materials and constructions have different forward voltage drops. For example, a Schottky diode typically drops less forward voltage than a silicon junction diode.
What electronic component allows current to flow in only one direction?
AnswerDiode
A diode conducts readily in its forward direction and blocks current in the reverse direction under normal operation.
Which of these components can be used as an electronic switch?
AnswerTransistor
A transistor can be driven between conducting and nonconducting states, allowing a small control signal to switch a larger current electronically.
Which of the following components can consist of three regions of semiconductor material?
AnswerTransistor
A bipolar transistor is built from three semiconductor regions arranged as either NPN or PNP material.
What type of transistor has a gate, drain, and source?
AnswerField-effect
A field-effect transistor controls current through a channel using a gate electrode. Its main terminals are gate, drain, and source.
How is the cathode lead of a semiconductor diode often marked on the package?
AnswerWith a stripe
Many diodes place a painted band or stripe at the cathode end of the package so polarity can be identified quickly.
What causes a light-emitting diode (LED) to emit light?
AnswerForward current
An LED emits light when it is forward biased and forward current flows through its semiconductor junction.
What does the abbreviation FET stand for?
AnswerField Effect Transistor
FET is the standard abbreviation for field-effect transistor, a transistor whose conduction is controlled by an electric field at its gate.
What are the names for the electrodes of a diode?
AnswerAnode and cathode
A diode has two electrodes: the anode and cathode. Conventional current flows from anode toward cathode when the diode is forward biased.
Which of the following can provide power gain?
AnswerTransistor
A transistor can control a larger output signal using a smaller input signal, which lets it provide amplification and power gain.
What does the term gain mean in amplifiers?
AnswerGain can mean output-to-input voltage, current, or power ratio.
Amplifier gain compares output with input. Depending on what is being measured, gain can describe voltage, current, or power ratio.
What are the names of the electrodes of a bipolar junction transistor?
AnswerEmitter, base, collector
A bipolar junction transistor has three electrodes: emitter, base, and collector. The base controls current between the other two terminals.
What is an electrical diagram using standard component symbols called?
AnswerSchematic
A schematic uses standardized electrical symbols and connecting lines to show how components are electrically related.
What is component 1 in figure T-1?
AnswerResistor
Component 1 in figure T-1 is the standard zigzag resistor symbol.
What is component 2 in figure T-1?
AnswerTransistor
Component 2 in figure T-1 is a transistor symbol, identifiable by its three semiconductor-terminal connections.
What is component 3 in figure T-1?
AnswerLamp
Component 3 in figure T-1 is the schematic symbol for a lamp or indicator bulb.
What is component 4 in figure T-1?
AnswerBattery
Component 4 in figure T-1 is the battery symbol, shown as alternating long and short parallel lines representing cells.
What is component 6 in figure T-2?
AnswerCapacitor
Component 6 in figure T-2 is the capacitor symbol, represented by two opposing conductive plates.
What is component 8 in figure T-2?
AnswerLight emitting diode
Component 8 in figure T-2 is an LED symbol: a diode symbol with arrows indicating emitted light.
What is component 9 in figure T-2?
AnswerVariable resistor
Component 9 in figure T-2 is a variable resistor. The added arrow indicates that its resistance can be adjusted.
What is component 4 in figure T-2?
AnswerTransformer
Component 4 in figure T-2 is a transformer, represented by magnetically coupled windings.
What is component 3 in figure T-3?
AnswerVariable inductor
Component 3 in figure T-3 is a variable inductor. The coil symbol shows inductance, and the diagonal arrow shows that it is adjustable.
What is component 4 in figure T-3?
AnswerAntenna
Component 4 in figure T-3 is the antenna symbol, indicating the circuit connection to an antenna or radiating element.
Which of the following is accurately represented in electrical schematics?
AnswerComponent connections
Schematics are designed to show electrical connections and circuit relationships. They do not normally preserve real wire lengths or the physical appearance of components.
Which of the following devices or circuits changes an alternating current into a varying direct current signal?
AnswerRectifier
A rectifier uses one-way semiconductor conduction to convert alternating current into a pulsating or varying direct-current waveform.
What is a relay?
AnswerAn electrically-controlled switch
A relay uses an electrical control signal to operate mechanical contacts, allowing one circuit to switch another.
Which of the following is a reason to use shielded wire?
AnswerTo prevent coupling of unwanted signals to or from the wire
A conductive shield intercepts electric fields and unwanted signal coupling. Shielded wire helps keep interference from entering or leaving the protected conductor.
Which of the following displays an electrical quantity as a numeric value?
AnswerMeter
A meter converts an electrical measurement into a displayed value so voltage, current, resistance, or another quantity can be read numerically.
What type of circuit controls the amount of voltage from a power supply?
AnswerRegulator
A voltage regulator keeps a power-supply output near a desired voltage despite reasonable changes in input voltage or load current.
What component changes 120 V AC power to a lower AC voltage for other uses?
AnswerTransformer
A transformer transfers AC energy magnetically between windings. A step-down transformer can convert 120 volts AC to a lower AC voltage.
Which of the following is commonly used as a visual indicator?
AnswerLED
An LED produces visible light efficiently when forward current flows, making it a common status and power indicator.
Which of the following is combined with an inductor to make a resonant circuit?
AnswerCapacitor
An inductor and capacitor exchange energy between magnetic and electric fields. Together they form an LC resonant or tuned circuit.
What is the name of a device that combines several semiconductors and other components into one package?
AnswerIntegrated circuit
An integrated circuit places multiple semiconductor devices and other circuit elements together in a single package or chip.
What is the function of component 2 in figure T-1?
AnswerControl the flow of current
Component 2 in figure T-1 is a transistor. In this circuit its role is to control the flow of current.
Which of the following is a resonant or tuned circuit?
AnswerAn inductor and a capacitor in series or parallel
A resonant circuit is formed by combining inductance and capacitance. At its resonant frequency, energy moves back and forth between the inductor's magnetic field and capacitor's electric field.