Deck 5: Special-Purpose Diodes Key

Question 1

What type of bias is required for normal operation of a zener diode?

A) reverse
B) forward
C) positive
D) negative

Answer 1

A

Question 2

A seven-segment display contains seven rectangular LEDs.

Answer 2

True

Question 3

Optoelectronics is the technology that combines audio and electronics.

Answer 3

False

Question 4

A zener diode is a silicon diode that operates in the breakdown region.

Question 5

The zener diode must remain in the breakdown region under all operating conditions in order for a zener regulator to hold the output voltage constant.

Question 6

What is the circuit shown in Figure 5-2 (a)?

A) RZ filter
B) zener regulator
C) voltage doubler
D) half-wave rectifier

Question 7

Commercial zener diodes have power ratings from ¼ to 500 W.

Question 8

The Schottky diode has metal on one side of the junction and therefore has no depletion layer.

Question 9

A shorted component is equivalent to a resistance of zero,and an open component is equivalent to a resistance of infinity.

Question 10

The zener diode data sheet rating,maximum current is the highest amount of current a zener diode can handle without exceeding its power rating.

Question 11

A circuit used when the desired dc output is less than the output of the power supply is a

A) zener regulator.
B) high-pass filter.
C) low-pass filter.
D) bridge rectifier.

Question 12

The positive resistance of tunnel diodes is useful in oscillator circuits.

Question 13

Step-recovery diodes are useful in frequency multiplier circuits.

Question 14

A varactor is a variable voltage multiplier.

Question 15

An optoisolator combines an LED and a photodiode is a single package.

Question 16

The power dissipation of a zener diode equals the product of its current and resistance.

Question 17

What is the purpose of R_S in Figure 5-2 (a)?

A) slow-blow fuse
B) limit resistance
C) limit current
D) step up voltage

Question 18

A varistor is a semiconductor device that operates like two back-to-back zener diodes with a high breakdown in both directions.

Question 19

The zener diode is the backbone of

A) constant current sources.
B) passive filters.
C) voltage regulators.
D) oscillator circuits.

Question 20

A zener diode is sometimes called a voltage-regulator diode because it maintains a constant output voltage even though the current through it changes.

Question 21

Examples of optoelectronic devices do not include ________.
A) LEDs

A) photodiodes
B) FETs
B) optocouplers

Question 22

The time it takes to turn off a forward-biased diode is called the
A) time constant.

A) turn-off time.
B) forward off-time.
B) reverse recovery time.

Question 23

The most important application of Schottky diodes is
A) in audio systems.

A) in digital computers.
B) television.
C) filter circuits.

Question 24

The manufacturer's data sheet entry that lists how much the power rating of a device must be reduced is the

A) maximum power dissipation.
B) reverse breakdown voltage.
C) power production factor.
D) derating factor.

Question 25

LEDs have breakdown voltages that typically range from
A) 1 to 2 V.

A) 3 to 5 V.
B) 6 to 10 V.
C) 10 to 15 V.

Question 26

As frequency increases,small-signal diodes are no longer able to
A) amplify ac signals.

A) switch off fast enough.
B) be forward biased.
C) serve as active filters.

Question 27

In order to maintain a constant output voltage,the zener diode

A) must be connected to a transformer.
B) must remain forward biased.
C) must remain in the breakdown region.
D) must be in series with a filter capacitor

Question 28

Zener diodes are available with power ratings that range from

A) ½ to more than 100 W.
B) ¼ to more than 50 W.
C) 1 to more than 10 W.
D) 1 to more than 100 W.

Question 29

What is the display device that contains seven rectangular LEDs?

A) CRT
B) liquid crystal display (LCD)
C) seven-segment display
D) laser

Question 30

What kind of diode has a metal such as gold or silver on one side of the junction and doped silicon on the other side?

A) tunnel
B) small-signal
C) Schottky
D) Zener

Question 31

What type of instrument can be used to test for a continuous path for current to flow?

A) voltmeter
B) ammeter
C) oscilloscope
D) continuity tester

Question 32

The Schottky diode has
A) a high reverse recovery time.

A) a large depletion layer_.
B) no depletion layer.
B) no junction.

Question 33

The basic idea of voltage regulation is that the output voltage remains the same
A) when power is turned off.

A) with virtually no change of input voltage.
B) even if a passive filter is used.
B) with considerable changes of input voltage.

Question 34

What type of cable is comprised of thin flexible fibers of glass or plastic that transmit light beams instead of free electrons?

A) coaxial
B) stranded copper cable
C) fiber-optic
D) wave guide

Question 35

The combination of an LED and a photodiode is called a(n)

A) seven-segment display.
B) laser.
C) LCD.
D) optocoupler.

Question 36

When a circuit is not operating as it should,troubleshooting generally begins by

A) removing solid-state components.
B) measuring resistances.
C) measuring voltages.
D) measuring currents.

Question 37

The Schottky diode is sometimes called a

A) silicon rectifier.
B) tunnel diode.
C) cold-carrier diode.
D) hot-carrier diode.

Question 38

A device used for electronic tuning and often used in television and FM receivers is a ________.

A) rectifier
B) Schottky diode
C) varactor
D) tuning fuse

Question 39

Which of the following is not an advantage of a light-emitting diode (LED)?

A) low voltage
B) long life
C) fast on-off switching
D) cost

Question 40

A device which is optimized for its sensitivity to light and has a window that lets light pass through the package to the junction is a
A) light-emitting diode.

A) tunnel diode.
B) incandescent bulb.
B) photodiode.

Question 41

With a varactor diode,the more it is reversed bias,its capacitance
A) decreases.

A) increases.
B) remains the same.
C) increases to 27 µF.

Question 42

The negative resistance of tunnel diodes make them useful in high-frequency circuits called

A) ________.oscilloscopes
B) amplifiers
C) rectifiers
D) oscillators

Question 43

What would the voltage be across R_L if C shorted?

A) ac
B) 120 Vdc
C) pulsating filtered dc
D) zero

Question 44

What is the output across R_L?

A) ac
B) 120 Vdc
C) pulsating filtered dc
D) zero

Question 45

A diode that conducts better in the reverse than in the forward direction is a(n)

A) optoisolator.
B) rectifier diode.
C) step-recovery diode.

Question 46

A varactor is often connected in parallel with an inductor to form a

A) bridge rectifier.
B) tunnel oscillator.
C) parallel resonant circuit.
D) parallelogram.

Question 47

A device that keeps the current through it fixed when the voltage changes is aA.zener diode.

A) silicon rectifier.
B) current-regulator diode.
B) tunnel diode.

Question 48

What is the purpose of V130LA2?
A) clip spikes

A) spike clips
B) pre-rectifier
C) voltage doubler

Question 49

The capacitance exhibited by a varactor diode is controlled by ________.
A) current

A) voltage
B) parallel circuits
C) resistance

Question 50

A diode that is useful in frequency multiplier circuits is a

A) slope diode.
B) photo diode.
C) zener diode.