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Semiconductors > Chapter 6 > Flashcards

Chapter 6 Flashcards

1
Q

The ____ section of a power supply works to provide a smoother DC output.

A.filter. B.Rectifier C. Voltage divider D.Voltage regulator

A

A.Filter

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2
Q

The AC component in a DC power supply is called ripple,and much of the ripple must be _____.
A.Increased. B.inverted. C.rectified. D.Removed

A

D.Removed

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3
Q

Which is hte most common type of capacitor used in power supplies?

A.Ceramic disc
B.Electrolytic
C.Mica
D.Paper

A

B.Electrolytic

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4
Q

The life of the capacitor will be greatly reduced if the applied voltage exceeds the voltage rating.

True or False

A

True

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5
Q

The voltage rating of a capactiro indicates the maximum amount of voltage the _____ is intended to withstand without breaking down.

A.Ceramic material
B.Charging electrodes
C.Conducdtove plates
D.dielectric

A

D.Dielectric

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6
Q

To be effective, a filter capacitor should completely discharge between half cycles.

True or False

A

False

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7
Q

What formula is used for determining the time constant of a capacitor filter circuit?

A

T=RC

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8
Q 
Another name for an inductive filter is a \_\_\_\_\_.
A.Choke
B.Coil
C.Condenser
D.Regulator
A

A.Choke

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9
Q

The inductive filter opposed change in _____ at the same rate that the capacitor opposes change in _____.

A.current/inductance
B.Current/voltage
C.voltage/current
D voltage/inductance

A

B.Current/voltage

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10
Q

How many time constants does it take for an inductor to reach maximum current induction?

A

5

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11
Q

A ________ allows lower frequency current to pass,while attenuating unwanted frequency currents.

A

Low-pass filter

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12
Q

_____ are best used with unregulated power supplies that have high current demands.

A.chokes
B.high pass filters
C.low-pass filters
D.regulators

A

A.chokes

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13
Q

The _____ in the circuit is used to regulate the power supply.

A

Zener diode

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14
Q

What type of device could also used to regulate the power supply?

A

Adjustable resistor

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15
Q

If a voltage doubler was applied to a circuit of 20 volts at 100 mA, the output would be 40 volts at ____mA.

A

50 mA

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16
Q

An LED generates lights because the _____ in its atoms of certain materials is of the frequencies of visible light.

A.electrons B.neutrons c.Protons. d.radiation

A

D.Radiation

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17
Q

An LED will only generate light when it is ____ biased.

A

Forward

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18
Q

_____ release energy that is below the visible light band and are commonly used in home electronics,such as remote controls.

A.infrared-emitting diodes
B.Light emitting diodes
C.photoresistors
D.phototransistors

A

A.Infrared-emitting diodes

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19
Q

LEDs and IREDs have a higher voltage drop than silicon diodes,usually around ___ to ____.

A

1.2v to 2.5v

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20
Q

LASER stands for _______.

A

Light Amplification by Stimulated Emission of Radiation.

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21
Q

With an incoherent light source, most waves are ____ of phase. In a later source, the waves are ____.

A

Out, in phase

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22
Q

_____ are used in communications where high optical energy is required to pass through lengthy fiber optic cables.

A.laser diodes
B.photo conductors
C.photo resistors
D.photo transistors

A

A.laser diodes

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23
Q

List the advantages of LEDs over laser diodes. (3)

A
  1. 10x the life expectancy
  2. 10x less in price
  3. They don’t require elaborate power supplies
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24
Q 
\_\_\_\_\_ are silicon devices that are sensitive to light.
A.ILEDs
B LEDs
C.photodiodes
D.photoresistors
A

C.photodiodes

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25
Q 
Photodiodes can operate in \_\_\_\_\_\_ mode.
A.isolation
B.photoconductive
C.photoresistive
D.photovoltaic
E. B or D
A

E.photoconductive and photovoltaic

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26
Q

The photodiode generates a voltage in response to light when in ______ mode.

A.isolation
B.photoconductive
C photoresistive
D.photovoltaic

A

D.photovoltaic

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27
Q 
The conductance of the diode changes when light is applied when in \_\_\_\_\_\_ mode.
A.isolation
B.photoconductive
C photoresistive
D.photovoltaic
A

B.photoconductive

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28
Q

A photodiode in photovoltaic mode is reverse biased. A photodiode in photoconductive mode is forward biased. True or False

A

False

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29
Q

Optocouplers, also called optoisolators, couple the light from a light-emitting device with a light-sensitive device
True or False

A

True

30
Q

Optocouplers optically couple a signal between two electrically isolated points.

A

True

31
Q 
Similar to the photodiode in photoconductive mode, the \_\_\_\_\_ changes its resistance when exposed to light changes.
Select one:
a. optocoupler 
b. optoisolator 
c. photolaser 
d. photoresistor
A

D.Photoresistor

32
Q

Which of the following design features must be included for a photocell to successfully work for many years?

I. Ability to withstand extreme temperatures
II. High operation cycle at rated load
III. Impact-resistive housing
IV. Lightning protection

A

b. I., II., III., and IV

33
Q

The ? conductor is the switch leg from a photoeye to a lighting contactor.

a. black
b. green
c. red
d. white

A

C.Red

34
Q

A polarized reflector changes the ? of the transmitter’s polarized beam as it reflects it back to the receiver.

A

Polarity

35
Q

Without a polarized reflector being used to change the polarity of the beam on a conveyor, a shiny object might fool the receiver into thinking the beam has not been broken.
True or False

A

True

36
Q

List 3 Advantages of photo-operated devices.

A
  1. No contact bounce problem
  2. Operate at very high speeds
  3. No mechanical parts to wear out
37
Q

? devices are imperative in high speed switching circuits.

A

Photoemissive

38
Q

The resistance of a(n) ? device reduces when exposed to light.

A

Photoconductive

39
Q

The most common photoconductive device is the_____.

A

cad cell

40
Q

What determines the amount of voltage produced by a photovoltaic cell?

A

The material it is made of.

41
Q

A forward biased diode that releases light energy is called a(n) ? .

A

Light emitting diode. (LED

42
Q

An optoelectronic device that emits light of one frequency or color is called a(n) ? .

A

Laser diode

43
Q

What is the proper name for a diode that emits infrared light when forward biased?

A

IRED

44
Q 
What type of diode is sensitive to light and exhibits less internal bias in the reverse bias mode when exposed to a light source?
A.ILED
B.Laser diode
C.LED
D.Photodiode
A

photodiode

45
Q

Photodiodes in photoconductive mode are normally operated in forward bias.
True or False

A

False

46
Q

A phototransistor is more sensitive to light than a photodarlington.
True or False

A

False

47
Q

Which light sensitive device could be used to switch AC current?

a. Optoisolator
b. Photodarlington
c. Photo-SCR
d. Phototriac

A

D.Phototriac

48
Q

The primary function of a(n) ? is to provide electrical separation between input and output signals.

a. optoisolator
b. photodarlington
c. photo-SCR
d. phototriac

A

A.optoisolator

49
Q

An optoelectronic device that emits monochromatic light is called a ?

a. laser diode
b. photodarlington
c. photo-SCR
d. phototriac

A

A.Laser diode

50
Q

The principle of operation of fiber optic cable is total internal reflection of light.
True or False

A

True

51
Q

When light strikes a transparent surface at less than the critical angle, the light is reflected.
True or False

A

False (refracted)

52
Q 
Which type of fiber is best suited for long distance high speed data applications?
Graded-index multimode fiber 
b. Graded-index single mode fiber 
c. Single-mode fiber
d. Step-index multimode fiber
A

C.Single mode fiber

53
Q

Fiber optic cables used for data transmission typically carry light signals at levels ? or less.

a. 25 µW
b. 50 µW
c. 75 µW I
d. 100 µW

A

D.100uW

54
Q

A current-controlled, three-terminal semiconductor device used for the control and amplification of electronic circuitry is called a(n) ? .

a. bipolar junction transistor
b. SCR
c. triac
d. unijunction transistor

A

A.Bipolar junction transistor

55
Q

The bipolar junction transistor is made up of either a NPN junction or a PNP junction.
True or False

A

True

56
Q

The relationship between the emitter current and the collector current in a BJT is called ? .

a. alpha
b. beta
c. cutoff
d. saturation

A

A.Alpha

57
Q

At ? , the transistor passes nearly no current across E-C (like an open switch).

a. alpha
b. beta
c. cutoff
d. saturation

A

C.Cutoff

58
Q

During ? , B-E is forward biased and C-E is reverse biased.

a. alpha
b. beta
c. cutoff
d. saturation

A

D.Saturation

59
Q

Which of the transistor configurations has a voltage phase reversal due to the collector voltage being 180° out of phase with the input base voltage?

a. Common base
b. Common collector
c. Common emitter
d. Emitter base

A

C.Common emmitter

60
Q

In normal operation of the BJT type transistor, the B-E junction must be reverse biased, and the C-B junction must be forward biased.
True or False

A

False

61
Q 
The   ?   is the most popular configuration, and application is universal.
A. common base 
b. common collector 
c. common emitter 
d. emitter base
A

c.common emitter

62
Q

Beta is the amount of DC current gain in a transistor. It is a relationship between the DC collector current to DC base current.
True or False

A

True

63
Q

Which transistor configuration is very useful as an isolation amplifier and is often called an emitter follower?

a. Common base
b. Common collector
c. Common emitter
d. Emitter base

A

B.Common Collector

64
Q

The PNP transistor is based on hole current where the NPN transistor is based on electron current.
True or False

A

True

65
Q

Why is the NPN transistor more widely used than the PNP? (3)

A
  1. Less expensive
  2. Better Flexibility
  3. Based on negative ground, which is more common
66
Q

Collector characteristic curves indicate changes in collector current with respect to changes in base current.

True or False

A

True

67
Q

The two extremes of a load line are saturation and cutoff points.
True or False

A

True

68
Q

3 methods to prevent transistor thermal instability

A
  1. Installation of heat sink
  2. Use of a feedback circuit
  3. Use of a voltage divider circuit
69
Q

What test instrument may be used to determine if a transistor is NPN or PNP type?

A

Digital multimeter

70
Q

When testing an NPN transistor with the ohmmeter leads connected (“− Collector” “+ Base”), one should be reading low resistance values.
True or False

A

True

Semiconductors (3 decks)

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