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Element 3 > SUB-ELEMENT C > Flashcards

SUB-ELEMENT C Flashcards

1
Q

What happens to the conductivity of photoconductive material when light shines on it?
A. It increases.
B. It decreases.
C. It stays the same.
D. It becomes temperature dependent.

A

A

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2
Q

What is the photoconductive effect?
A. The conversion of photon energy to electromotive energy.
B. The increased conductivity of an illuminated semiconductor junction.
C. The conversion of electromotive energy to photon energy.
D. The decreased conductivity of an illuminated semiconductor junction.

A

B

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3
Q

What does the photoconductive effect in crystalline solids produce a noticeable change in?
A. The capacitance of the solid.
B. The inductance of the solid.
C. The specific gravity of the solid.
D. The resistance of the solid.

A

D

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4
Q

What is the description of an optoisolator?
A. An LED and a photosensitive device.
B. A P-N junction that develops an excess positive charge when exposed to light.
C. An LED and a capacitor.
D. An LED and a lithium battery cell.

A

A

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5
Q

What happens to the conductivity of a photosensitive semiconductor junction when it is illuminated?
A. The junction resistance is unchanged.
B. The junction resistance decreases.
C. The junction resistance becomes temperature dependent.
D. The junction resistance increases

A

B

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6
Q

What is the description of an optocoupler?
A. A resistor and a capacitor.
B. Two light sources modulated onto a mirrored surface.
C, An LED and a photosensitive device.
D. An amplitude modulated beam encoder.

A

C

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7
Q

What factors determine the capacitance of a capacitor?
A. Voltage on the plates and distance between the plates.
B. Voltage on the plates and the dielectric constant of the material between the plates.
C. Amount of charge on the plates and the dielectric constant of the material between the plates.
D. Distance between the plates and the dielectric constant of the material between the plates.

A

D

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8
Q

In Figure 3C4, if a small variable capacitor were installed in place of the dashed line, it would?
A. Increase gain.
B. Increase parasitic oscillations.
C. Decrease parasitic oscillations.
D. Decrease crosstalk.

A

C

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9
Q

In Figure 3C4, which component (labeled 1 through 4) is used to provide a signal ground?
A. 1
B. 2
C. 3
D. 4

A

B

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10
Q

In Figure 3C5, which capacitor (labeled 1 through 4) is being used as a bypass capacitor?
A. 1
B. 2
C. 3
D. 4

A

C

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11
Q

In Figure 3C5, the 1 μF capacitor is connected to a potentiometer that is used to:
A. Increase gain.
B. Neutralize amplifier.
C. Couple.
D. Adjust tone.

A

D

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12
Q

What is the purpose of a coupling capacitor?
A. It blocks direct current and passes alternating current.
B. It blocks alternating current and passes direct current.
C. It increases the resonant frequency of the circuit.
D. It decreases the resonant frequency of the circuit.

A

A

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13
Q

A capacitor is sometimes placed in series with the primary of a power transformer to:
A. Improve the power factor.
B. Improve output voltage regulation.
C. Rectify the primary windings.
D. None of these.

A

A

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14
Q

A transformer used to step up its input voltage must have:
A. More turns of wire on its primary than on its secondary.
B. More turns of wire on its secondary than on its primary.
C. Equal number of primary and secondary turns of wire.
D. None of the above statements are correct.

A

B

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15
Q

A transformer primary of 2250 turns connected to 120 VAC will develop what voltage across a 500-turn secondary?
A. 26.7 volts.
B. 2300 volts.
C. 1500 volts.
D. 5.9 volts.

A

A

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16
Q

What is the ratio of the output frequency to the input frequency of a single-phase full-wave rectifier?
A. 1:1.
B. 1:2.
C. 2:1.
D. None of these.

A

C

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17
Q

A power transformer has a single primary winding and three secondary windings producing 5.0 volts, 12.6 volts, and 150 volts. Assuming similar wire sizes, which of the three secondary windings will have the highest measured DC resistance?
A. The 12.6 volt winding.
B. The 150 volt winding.
C. The 5.0 volt winding.
D. All will have equal resistance values.

A

B

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18
Q

A power transformer has a primary winding of 200 turns of #24 wire and a secondary winding consisting of 500 turns of the same size wire. When 20 volts are applied to the primary winding, the expected secondary voltage will be:
A. 500 volts.
B. 25 volts.
C. 10 volts.
D. 50 volts.

A

D

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19
Q

In a linear electronic voltage regulator:
A. The output is a ramp voltage.
B. The pass transistor switches from the “off” state to the “on”” state.
C. The control device is switched on or off, with the duty cycle proportional to the line or load conditions.
D. The conduction of a control element is varied in direct proportion to the line voltage or load current.

A

D

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20
Q

A switching electronic voltage regulator:
A. Varies the conduction of a control element in direct proportion to the line voltage or load current.
B. Provides more than one output voltage.
C. Switches the control device on or off, with the duty cycle proportional to the line or load conditions.
D. Gives a ramp voltage at its output.

A

C

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21
Q

What device is usually used as a stable reference voltage in a linear voltage regulator?
A. Zener diode.
B. Tunnel diode.
C. SCR.
D. Varactor diode.

A

A

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22
Q

In a regulated power supply, what type of component will most likely be used to establish a reference voltage?
A. Tunnel Diode.
B. Battery.
C. Pass Transistor.
D. Zener Diode.

A

D

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23
Q

A three-terminal regulator:
A. Supplies three voltages with variable current.
B. Supplies three voltages at a constant current.
C. Contains a voltage reference, error amplifier, sensing resistors and transistors, and a pass element.
D. Contains three error amplifiers and sensing transistors.

A

C

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24
Q

What is the range of voltage ratings available in Zener diodes?
A. 1.2 volts to 7 volts.
B. 2.4 volts to 200 volts and above.
C. 3 volts to 2000 volts.
D. 1.2 volts to 5.6 volts.

A

B

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25
Q

How might two similar SCRs be connected to safely distribute the power load of a circuit?
A. In series.
B. In parallel, same polarity.
C. In parallel, reverse polarity.
D. In a combination series and parallel configuration.

A

C

26
Q

What are the three terminals of an SCR?
A. Anode, cathode, and gate.
B. Gate, source, and sink.
C. Base, collector, and emitter.
D. Gate, base 1, and base 2.

A

A

27
Q

Which of the following devices acts as two SCRs connected back to back, but facing in opposite directions and sharing a common gate?
A. JFET.
B. Dual-gate MOSFET.
C. DIAC.
D. TRIAC.

A

D

28
Q

What is the transistor called that is fabricated as two complementary SCRs in parallel with a common gate terminal?
A. TRIAC.
B. Bilateral SCR.
C. Unijunction transistor.
D. Field effect transistor.

A

A

29
Q

What are the three terminals of a TRIAC?
A. Emitter, base 1, and base 2.
B. Base, emitter, and collector.
C. Gate, source, and sink.
D. Gate, anode 1, and anode 2.

A

D

30
Q

What circuit might contain a SCR?
A. Filament circuit of a tube radio receiver.
B. A light-dimming circuit.
C. Shunt across a transformer primary.
D. Bypass capacitor circuit to ground.

A

B

31
Q

What is one common use for PIN diodes?
A. Constant current source.
B. RF switch.
C. Constant voltage source.
D. RF rectifier.

A

B

32
Q

What is a common use of a hot-carrier diode?
A. Balanced inputs in SSB generation.
B. Variable capacitance in an automatic frequency control circuit.
C. Constant voltage reference in a power supply.
D. VHF and UHF mixers and detectors.

A

D

33
Q

Structurally, what are the two main categories of semiconductor diodes?
A. Junction and point contact.
B. Electrolytic and junction.
C. Electrolytic and point contact.
D. Vacuum and point contact.

A

A

34
Q

What special type of diode is capable of both amplification and oscillation?
A. Zener diodes.
B. Point contact diodes.
C. Tunnel diodes.
D. Junction diodes.

A

C

35
Q

What type of semiconductor diode varies its internal capacitance as the voltage applied to its terminals varies?
A. Tunnel diode.
B. Varactor diode.
C. Silicon-controlled rectifier.
D. Zener diode.

A

B

36
Q

What is the principal characteristic of a tunnel diode?
A. High forward resistance.
B. Very high PIV(peak inverse voltage).
C. Negative resistance region.
D. High forward current rating.

A

C

37
Q

What is the meaning of the term “alpha” with regard to bipolar transistors? The change of:
A. Collector current with respect to base current.
B. Base current with respect to collector current.
C. Collector current with respect to gate current.
D. Collector current with respect to emitter current.

A

D

38
Q

What are the three terminals of a bipolar transistor?
A. Cathode, plate and grid.
B. Base, collector and emitter.
C. Gate, source and sink.
D. Input, output and ground.

A

B

39
Q

What is the meaning of the term “beta” with regard to bipolar transistors? The change of:
A. Base current with respect to emitter current.
B. Collector current with respect to emitter current.
C. Collector current with respect to base current.
D. Base current with respect to gate current.

A

C

40
Q

What are the elements of a unijunction transistor?
A. Base 1, base 2, and emitter.
B. Gate, cathode, and anode.
C. Gate, base 1, and base 2.
D. Gate, source, and sink.

A

A

41
Q

The beta cutoff frequency of a bipolar transistor is the frequency at which:
A. Base current gain has increased to 0.707 of maximum.
B. Emitter current gain has decreased to 0.707 of maximum.
C. Collector current gain has decreased to 0.707.
D. Gate current gain has decreased to 0.707.

A

B

42
Q

What does it mean for a transistor to be fully saturated?
A. The collector current is at its maximum value.
B. The collector current is at its minimum value.
C. The transistor’s Alpha is at its maximum value.
D. The transistor’s Beta is at its maximum value.

A

A

43
Q

A common base amplifier has:
A. More current gain than common emitter or common collector.
B. More voltage gain than common emitter or common collector.
C. More power gain than common emitter or common collector.
D. Highest input impedance of the three amplifier configurations.

A

B

44
Q

What does it mean for a transistor to be cut off?
A. There is no base current.
B. The transistor is at its Class A operating point.
C. There is no current between emitter and collector.
D. There is maximum current between emitter and collector.

A

C

45
Q

An emitter-follower amplifier has:
A. More voltage gain than common emitter or common base.
B. More power gain than common emitter or common base.
C. Lowest input impedance of the three amplifier configurations.
D. More current gain than common emitter or common base.

A

D

46
Q

What conditions exists when a transistor is operating in saturation?
A. The base-emitter junction and collector-base junction are both forward biased.
B. The base-emitter junction and collector-base junction are both reverse biased.
C. The base-emitter junction is reverse biased and the collector-base junction is forward biased.
D. The base-emitter junction is forward biased and the collector-base junction is reverse biased.

A

A

47
Q

For current to flow in an NPN silicon transistor’s emitter-collector junction, the base must be:
A. At least 0.4 volts positive with respect to the emitter.
B. At a negative voltage with respect to the emitter.
C. At least 0.7 volts positive with respect to the emitter.
D. At least 0.7 volts negative with respect to the emitter.

A

C

48
Q

When an NPN transistor is operating as a Class A amplifier, the base-emitter junction:
A. And collector-base junction are both forward biased.
B. And collector-base junction are both reverse biased.
C. Is reverse biased and the collector-base junction is forward biased.
D. Is forward biased and the collector-base junction is reverse biased.

A

D

49
Q

What type of bias is required for an LED to produce luminescence?
A. Reverse bias.
B. Forward bias.
C. Logic 0 (Lo) bias.
D. Logic 1 (Hi) bias.

A

B

50
Q

What determines the visible color radiated by an LED junction?
A. The color of a lens in an eyepiece.
B. The amount of voltage across the device.
C. The amount of current through the device.
D. The materials used to construct the device.

A

D

51
Q

What is the approximate operating current of a light-emitting diode?
A. 20 mA.
B. 5 mA.
C. 10 mA.
D. 400 mA.

A

A

52
Q

What would be the maximum current to safely illuminate a LED?
A. 1 amp.
B. 1 microamp.
C. 500 milliamps.
D. 20 mA.

A

D

53
Q

An LED facing a photodiode in a light-tight enclosure is commonly known as a/an:
A. Optoisolator.
B. Seven segment LED.
C. Optointerrupter.
D. Infra-red (IR) detector.

A

A

54
Q

What circuit component must be connected in series to protect an LED?
A. Bypass capacitor to ground.
B. Electrolytic capacitor.
C. Series resistor.
D. Shunt coil in series.

A

C

55
Q

What describes a diode junction that is forward biased?
A. It is a high impedance.
B. It conducts very little current.
C. It is a low impedance.
D. It is an open circuit.

A

C

56
Q

Why are special precautions necessary in handling FET and CMOS devices?
A. They have fragile leads that may break off.
B. They are susceptible to damage from static charges.
C. They have micro-welded semiconductor junctions that are susceptible to breakage.
D. They are light sensitive.

A

B

57
Q

What do the initials CMOS stand for?
A. Common mode oscillating system.
B. Complementary mica-oxide silicon.
C. Complementary metal-oxide semiconductor.
D. Complementary metal-oxide substrate.

A

C

58
Q

What is the piezoelectric effect?
A. Mechanical vibration of a crystal by the application of a voltage.
B. Mechanical deformation of a crystal by the application of a magnetic field.
C. The generation of electrical energy by the application of light.
D. Reversed conduction states when a P-N junction is exposed to light.

A

A

59
Q

An electrical relay is a:
A. Current limiting device.
B. Device used for supplying 3 or more voltages to a circuit.
C. Component used mainly with HF audio amplifiers.
D. Remotely controlled switching device.

A

D

60
Q

In which oscillator circuit would you find a quartz crystal?
A. Hartley.
B. Pierce
C. Colpitts.
D. All of the above.

A

B

Element 3 (17 decks)

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