Chapter 6 Flashcards
The ____ section of a power supply works to provide a smoother DC output.
A.filter. B.Rectifier C. Voltage divider D.Voltage regulator
A.Filter
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
D.Removed
Which is hte most common type of capacitor used in power supplies?
A.Ceramic disc
B.Electrolytic
C.Mica
D.Paper
B.Electrolytic
The life of the capacitor will be greatly reduced if the applied voltage exceeds the voltage rating.
True or False
True
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
D.Dielectric
To be effective, a filter capacitor should completely discharge between half cycles.
True or False
False
What formula is used for determining the time constant of a capacitor filter circuit?
T=RC
Another name for an inductive filter is a \_\_\_\_\_. A.Choke B.Coil C.Condenser D.Regulator
A.Choke
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
B.Current/voltage
How many time constants does it take for an inductor to reach maximum current induction?
5
A ________ allows lower frequency current to pass,while attenuating unwanted frequency currents.
Low-pass filter
_____ 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.chokes
The _____ in the circuit is used to regulate the power supply.
Zener diode
What type of device could also used to regulate the power supply?
Adjustable resistor
If a voltage doubler was applied to a circuit of 20 volts at 100 mA, the output would be 40 volts at ____mA.
50 mA
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
D.Radiation
An LED will only generate light when it is ____ biased.
Forward
_____ 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.Infrared-emitting diodes
LEDs and IREDs have a higher voltage drop than silicon diodes,usually around ___ to ____.
1.2v to 2.5v
LASER stands for _______.
Light Amplification by Stimulated Emission of Radiation.
With an incoherent light source, most waves are ____ of phase. In a later source, the waves are ____.
Out, in phase
_____ 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.laser diodes
List the advantages of LEDs over laser diodes. (3)
- 10x the life expectancy
- 10x less in price
- They don’t require elaborate power supplies
\_\_\_\_\_ are silicon devices that are sensitive to light. A.ILEDs B LEDs C.photodiodes D.photoresistors
C.photodiodes
Photodiodes can operate in \_\_\_\_\_\_ mode. A.isolation B.photoconductive C.photoresistive D.photovoltaic E. B or D
E.photoconductive and photovoltaic
The photodiode generates a voltage in response to light when in ______ mode.
A.isolation
B.photoconductive
C photoresistive
D.photovoltaic
D.photovoltaic
The conductance of the diode changes when light is applied when in \_\_\_\_\_\_ mode. A.isolation B.photoconductive C photoresistive D.photovoltaic
B.photoconductive
A photodiode in photovoltaic mode is reverse biased. A photodiode in photoconductive mode is forward biased. True or False
False
Optocouplers, also called optoisolators, couple the light from a light-emitting device with a light-sensitive device
True or False
True
Optocouplers optically couple a signal between two electrically isolated points.
True
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
D.Photoresistor
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
b. I., II., III., and IV
The ? conductor is the switch leg from a photoeye to a lighting contactor.
a. black
b. green
c. red
d. white
C.Red
A polarized reflector changes the ? of the transmitter’s polarized beam as it reflects it back to the receiver.
Polarity
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
True
List 3 Advantages of photo-operated devices.
- No contact bounce problem
- Operate at very high speeds
- No mechanical parts to wear out
? devices are imperative in high speed switching circuits.
Photoemissive
The resistance of a(n) ? device reduces when exposed to light.
Photoconductive
The most common photoconductive device is the_____.
cad cell
What determines the amount of voltage produced by a photovoltaic cell?
The material it is made of.
A forward biased diode that releases light energy is called a(n) ? .
Light emitting diode. (LED
An optoelectronic device that emits light of one frequency or color is called a(n) ? .
Laser diode
What is the proper name for a diode that emits infrared light when forward biased?
IRED
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
photodiode
Photodiodes in photoconductive mode are normally operated in forward bias.
True or False
False
A phototransistor is more sensitive to light than a photodarlington.
True or False
False
Which light sensitive device could be used to switch AC current?
a. Optoisolator
b. Photodarlington
c. Photo-SCR
d. Phototriac
D.Phototriac
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.optoisolator
An optoelectronic device that emits monochromatic light is called a ?
a. laser diode
b. photodarlington
c. photo-SCR
d. phototriac
A.Laser diode
The principle of operation of fiber optic cable is total internal reflection of light.
True or False
True
When light strikes a transparent surface at less than the critical angle, the light is reflected.
True or False
False (refracted)
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
C.Single mode fiber
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
D.100uW
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.Bipolar junction transistor
The bipolar junction transistor is made up of either a NPN junction or a PNP junction.
True or False
True
The relationship between the emitter current and the collector current in a BJT is called ? .
a. alpha
b. beta
c. cutoff
d. saturation
A.Alpha
At ? , the transistor passes nearly no current across E-C (like an open switch).
a. alpha
b. beta
c. cutoff
d. saturation
C.Cutoff
During ? , B-E is forward biased and C-E is reverse biased.
a. alpha
b. beta
c. cutoff
d. saturation
D.Saturation
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
C.Common emmitter
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
False
The ? is the most popular configuration, and application is universal. A. common base b. common collector c. common emitter d. emitter base
c.common emitter
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
True
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
B.Common Collector
The PNP transistor is based on hole current where the NPN transistor is based on electron current.
True or False
True
Why is the NPN transistor more widely used than the PNP? (3)
- Less expensive
- Better Flexibility
- Based on negative ground, which is more common
Collector characteristic curves indicate changes in collector current with respect to changes in base current.
True or False
True
The two extremes of a load line are saturation and cutoff points.
True or False
True
3 methods to prevent transistor thermal instability
- Installation of heat sink
- Use of a feedback circuit
- Use of a voltage divider circuit
What test instrument may be used to determine if a transistor is NPN or PNP type?
Digital multimeter
When testing an NPN transistor with the ohmmeter leads connected (“− Collector” “+ Base”), one should be reading low resistance values.
True or False
True
