REM B LVL 1 Flashcards by Dave Molina

Assertion (A): Silicon is less sensitive to
changes in temperature than
germanium.
Reason (R): It is more difficult to
produce minority carriers in silicon than
in germanium.

A. A is false but R is true
B. Both A and R are true but R is not a correct
explanation of A
C. Both A and R are true and R is correct
explanation of A

C. Both A and R are true and R is correct
explanation of A

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Assertion (A): The conductivity of p type
semiconductor is higher than that of
intrinsic semiconductor.
Reason (R): The addition of donor
impurity creates additional energy levels
below conduction band.

A. A is false but R is true
B. A is true but R is false
C. Both A and R are true and R is correct
explanation of A
D. Both A and R are true but R is not a
correct explanation of A

D. Both A and R are true but R is not a
correct explanation of A

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Which of the following is true for
Pentavalent impurities?

A. Have three valence electrons
B. Introduce holes when added to a
semiconductor material
C. Increase the conduction of a
semiconductror material

C. Increase the conduction of a
semiconductror material

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When a diode in a center-tapped
rectifier opens, the output is

A. unaffected
B. 0V
C. half-wave rectified

C. half-wave rectified

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What band is characterized by the
existence of the forbidden band narrow
enough to allow terminal transition in
the next allowed band?

A. Conductor
B. Plasma
C. Inductor

A. Conductor

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A semiconductor diode is biased in
forward direction and carrying current I.
The current due to holes in p material is

A. less than I
B. 0
C. 0.5

A. less than I

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Assertion (A): When a photoconductive
device is exposed to light, its bulk
resistance increases.
Reason (R): When exposed to light,
electron hole pairs are generated in the
photoconductive device.

A. A is true but R is false
B. Both A and R are true but R is not a correct
explanation of A
C. A is false but R is true

C. A is false but R is true

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Fig. 8-12-5-A6 represents a…

(REM ELEX B LVL 1 FIGURE)

Fig. 8-12-5-A6

A. Varistor
B. Schottky diode
C. None of these choices
D. Diode rectifier

B. Schottky diode

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If the capacitor from emitter to ground
in a Common Emitter amplifier is
removed, the voltage gain

A. increases
B. becomes erratic
C. decreases
D. is not affected

C. decreases

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The SI units of transconductance is

A. Ohm
B. Volt/ ampere
C. Ampere/ volt

C. Ampere/ volt

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In a common-emitter (CE) amplifier, the
capacitor from emitter to ground is
called the ___ capacitor.

A. tuning
B. coupling
C. bypass
D. decoupling

C. bypass

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Which of the following models of diode equivalent circuit is represented by the given I-V characteristic curve?

(REM ELEX B LVL 1 FIGURE)

A. Hybrid model
B. Simplified Model
C. Ideal Diode Model
D. Piecewise Linear Model

B. Simplified Model

In simplified model, the value of rd is
neglected and hence, we get a high
value of current for voltage greater than
or equal to VT.

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In a regulated supply, what term
describes how much change occurs in the output voltage for a given change in the input voltage?

A. ripple voltage
B. load regulation
C. line regulation
D. voltage regulator

C. line regulation

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During the positive half-cycle of the
input voltage in a bridge rectifier,

A. two diodes are forward-biased
B. all diodes are forward-biased
C. all diodes are reverse-biased

A. two diodes are forward-biased

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A Zener diode is in a ___
impedance region in the forward bias
while it has a ___ impedance region
in the reverse bias.

A. very large, low
B. low, low
C. very large, very large
D. low, very large

D. low, very large

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Typical values of voltage amplification
for the common-base configurations
vary from ___ and the current gain
is always ___

A. 50 to 300, larger than 1
B. 50 to 300, less than 1
C. larger than 1, 50 to 300

B. 50 to 300, less than 1

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The full-wave voltage doubler provides
___ filtering action than (as) the
half-wave voltage doubler.

A. None of these choices
B. better
C. poorer

B. better

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In a voltage regulator network with fixed
RL and R, what element dictates the
minimum level of source voltage?

A. Vz
B. Iz
C. Tz

A. Vz

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If the base current of a transistor
operates in the linear region increases,
the collector current ___ and the
emitter current ___

A. Decreases, decreases
B. Increases, increases
C. Increases, decreases
D. Increases, does not change

B. Increases, increases

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In a PNP circuit, the collector:

A. Has an arrow pointing inward
B. Is biased at a small fraction of the base
bias
C. Is positive with respect to the emitter
D. Is negative with respect to the emitter

D. Is negative with respect to the emitter

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In normal operation an n-p-n transistor
connected in common-base
configuration has

A. the collector at a lower potential than the
emitter
B. the emitter at a lower potential than the
base
C. the base at a lower potential than the
emitter

B. the emitter at a lower potential than the
base

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In Fig. Fig. 12-5-9-A5.If R_E short-
circuited:
(REM ELEX B LVL 1 FIGURE)

Fig. 12-5-9-A5

A. the load line would be affected
B. the load line would be unaffected
C. neither the load line would be unaffected
and the load line would be affected
D. both the load line would be unaffected and
the load line would be affected

A. the load line would be affected

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The most stable biasing technique used
is the

A. collector bias.
B. voltage-divider bias.
C. base bias.

B. voltage-divider bias.

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The output, V-I characteristics of an
Enhancement type MOSFET has

A. only a saturation region
B. an ohmic region at low voltage value
followed by a saturation region at
higher voltages
C. only an ohmic region

B. an ohmic region at low voltage value
followed by a saturation region at
higher voltages

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The input resistance of the base of a voltage-divider biased transistor can be neglected A. only if the base current is much larger than the current through R2 (the lower bias resistor). B. only if the base current is much smaller than the current through R2 (the lower bias resistor). C. at all times.

B. only if the base current is much smaller than the current through R2 (the lower bias resistor).

How many individual pnp silicon transistors can be housed in a 14-pin plastic dual-in-line package? A. 4 B. 14 C. 10

A. 4

Assertion (A): In a BJT, the base region is very thick. Reason (R): In p-n-p transistor most of holes given off by emitter diffuse through the base. A. A is true but R is falseA is false but R is true B. A is false but R is true C. Both A and R are true and R is correct explanation of A

C. Both A and R are true and R is correct explanation of A

For which of the following frequency region(s) can the coupling and bypass capacitors no longer be replaced by the short-circuit approximation? A. Low-frequency B. All of these choices C. Mid-frequency

A. Low-frequency

The largest theoretical voltage gain obtainable with a CC amplifier is A. unity B. 100 C. infinite D. 10

A. unity

In an RC coupled CE amplifier, when the input frequency increases, which of these are incorrect? A. An RC coupled amplifier behaves like a low pass filter B. Voltage gain increases C. Voltage gain decreases due to shunt capacitance D. Reactance CsH decreases

B. Voltage gain increases When frequency increases, shunt reactance decreases. The voltage drop across shunt capacitance decreases and net voltage gain decrease. RC coupled amplifier acts as a low pass filter at high frequencies.

What is the purpose of using a cascading transistor configuration? A. Decrease current gain B. Decrease voltage gain C. Increase current gain D. Increase voltage gain

D. Increase voltage gain A circuit having a single transistor configuration does not provide suitable bandwidth or gain. The purpose of a cascading transistor configuration is to provide an increase in the voltage gain.The total gain of a cascading transistor configuration is the product of the voltage gains of the discrete stages.

A number of op-amp stages can be used to provide separate gains. A. lacks data B. True C. False

B. True

What is the advantage of using a cascading transistor configuration? A. High gain and high bandwidth B. Low gain and high bandwidth C. Low gain and low bandwidth

A. High gain and high bandwidth A circuit having a single transistor configuration does not provide suitable bandwidth or gain. To overcome this difficulty, we combine several amplification stages. The cascading transistor configuration theory is used for high gain as well as high bandwidth.

— build a multistage connection. A. Neither inverting nor noninverting op-amp circuits must be used to B. Both inverting and noninverting op-amp circuits can be used to C. Only a noninverting op-amp circuit must be used to

B. Both inverting and noninverting op-amp circuits can be used to

For any cascaded amplifier network, which of these are incorrect? A. The overall output resistance is less than the lowest output resistance in all amplifiers used B. Overall input resistance is equal to the input resistance of the first amplifier C. Loading effect occurs

A. The overall output resistance is less than the lowest output resistance in all amplifiers used In cascading, the output of one amplifier is connected to the input of another amplifier. It is used to increase gain while obtaining desired values of input and output resistances. Overall input resistance is the same as input resistance of the first amplifier and net output resistance is the same as output resistance of the last (n) amplifier in the network. When amplifiers are connected in cascade, then loading effect does occur.

What is the need for bootstrap biasing? A. To prevent a decrease in the input resistance due to the biasing network B. To prevent an increase in the input resistance due to the biasing network C. To prevent a decrease in the input resistance due to the presence of multiple BJT amplifiers

A. To prevent a decrease in the input resistance due to the biasing network A bootstrap biasing network is a special biasing circuit used in the Darlington amplifier to prevent the decrease in input resistance due to the biasing network being used. Capacitors and resistors are added to the circuit to prevent it from happening.

How is the voltage gain measured in a cascading transistor configuration? A. Decibels B. Ampere C. Dimensionless

A. Decibels The voltage gain is measured in terms of decibels. The total voltage gain is calculated as the product of individual stages or as a sum of all the stages if the gain calculated at each intermediate stage was measured in decibels as well.

A widlar current source is used A. to get high value of Output B. to get high value of CMRR C. to get low value of current

C. to get low value of current In the widlar current source Re is added to emitter lead of transistor, which consequently results in smaller output current value.

The purpose of a comparator is to A. detect the occurrence of a changing input voltage B. amplify an input voltage C. produce a change in output when an input voltage equals a reference voltage D. maintain a constant output when the dc input voltage changes

C. produce a change in output when an input voltage equals a reference voltage

If you know an op-amp's open-loop gain and nothing else, you can determine the closed-loop gain of A. an inverting amplifier B. a noninverting amplifier C. a voltage-follower D. none of the amplifier configurations without additional information

C. a voltage-follower

In selecting an op-amp, suppose you have several choices. Of the CMRR values listed, the most desirable is A. 20 dB B. 10 dB C. 100 dB

C. 100 dB

The feedback path in an ideal op-amp integrator consists of a A. capacitor B. resistor and a capacitor in series C. resonant circuit D. resistor

A. capacitor

The purpose of a comparator is to A. produce a change in output when an input voltage equals a reference voltage B. maintain a constant output when the dc input voltage changes C. detect the occurrence of a changing input voltage

A. produce a change in output when an input voltage equals a reference voltage

In an oscillator circuit, the feedback should be: A. As great as possible B. Kept to a minimum C. Just enough to sustain oscillation

C. Just enough to sustain oscillation

A tapped coil is used in a (n): A. Clapp oscillator B. Hartley oscillator C. Armstrong oscillator D. Colpitts oscillator

B. Hartley oscillator

Feedback oscillators operate on the principle of A. attenuation B. signal feedthrough C. positive feedback D. negative feedback

C. positive feedback

Negative feedback in an amplifier: A. Is used in an Armstrong oscillator B. Causes oscillation C. Increases sensitivity D. Reduces the gain

D. Reduces the gain

In the Wien bridge oscillator, which of the following is (are) frequency- determining components? A. C1 and C2 B. R1 and R2 C. None of these choices D. R1, R2, C1, and C2

D. R1, R2, C1, and C2

Which of the following improvements is(are) a result of the negative feedback in a circuit? A. Better stabilized voltage gain B. All of these choices C. Higher input impedance

B. All of these choices

Which of the following is not a characteristic of the UJT? A. negative resistance B. peak-point voltage C. bilateral conduction D. intrinsic standoff ratio

C. bilateral conduction

Thyristors can be used for control of A. dc separately excited motor B. dc shunt motor C. all of these choices D. dc series motor

C. all of these choices

Your boss has asked you to recommend a thyristor that will enable you to turn it on with a pulse and also turn it off with a pulse. Which of the following should you recommend? A. a triac B. an SCR C. a PUT D. an SCS

D. an SCS

Identify the triac. (REM ELEX B LVL 1 FIGURE) A. d B. e C. a D. d

B. e

You need a very efficient thyristor to control the speed of an AC fan motor. A good device to use would be A. a triac B. a 4-layer diode C. a BJT D. a PUT

A. a triac

The converter circuit which employs turn on and turn off when the voltage and/or current through the device is zero at the instant of switching is ___ A. a conventional converter B. none of these choices C. a resonant converter D. a zero switching circuit

C. a resonant converter

You have a light-dimmer circuit using an SCR. In testing the circuit, you find that 1G = O mA and the light is still on. You conclude that the trouble might be one of the following: A. the switch is faulty B. the SCR is open C. the gate circuit is shorted D. this is normal; nothing is wrong

D. this is normal; nothing is wrong

Which of the following is NOT an analog device? A. Thermocouple B. Current flow in a circuit C. Light switch D. Audio microphone

C. Light switch

An application of a(n) ___ is in a lighting system for power interruptions. A. triac B. diac C. SCS D. SCR

D. SCR

What is the effect on properties of LDR when light falls on it? A. Its capacitance changes B. Its resistance remains same C. Its resistance changes

C. Its resistance changes When light falls on LDR (Light dependant resistor) its resistance changes. It is inversely proportional to the intensity of light. When light falls on LDR, the resistance decreases and more current starts to flow through it. It is used to measure the intensity of light.

What are transducers? A. They convert work to power B. They convert energy from one form to another C. They convert power from one form to another D. They convert work from one form to another

B. They convert energy from one form to another Transducer are devices that convert energy from one form to another. This energy can be either mechanical energy, light energy, heat energy or any other forms of energy.

What type of energy conversion does a piezoelectric transducer perform? A. It converts mechanical energy to electrical energy B. It converts electrical energy to mechanical energy C. It converts mechanical energy to sound energy D. It converts sound energy to mechanical energy

A. It converts mechanical energy to electrical energy A piezoelectric transducer converts mechanical energy to electrical energy. They are generally used to detect a knock or any impulsive force. They are also used in electronic drum pads to detect the impulse provided by the drumsticks.

PLC operates on the following signals A. Digital B. Analog C. Frequency

A. Digital

Which of the following are criteria for selecting a PLC or Programmable Logic Controller? 1. Input and output capacity 2. Size of memory needed 3. Speed and power of CPU 4. Physical and environmental conditions A. 1,2, and 3 only B. 1.2,3, and 4 C. 1 and 3 only

B. 1.2,3, and 4

Solid State Relays (SSRs) have a A. scr B. optocoupler C. none of these choices

B. optocoupler

In a ladder logic, the given symbol is used to indicate ___ A. Heating element B. Relay coil C. Fuse

A. Heating element

The design concept of using building blocks of circuits in a PLD program is called a(n): A. digital design B. architectural design C. verilog D. hierarchical design

D. hierarchical design

HVDC transmission has ___ as compared to HVAC transmission. A. smaller conductor size B. smaller transformer size C. smaller power transfer capabilities

A. smaller conductor size

In an analog switch, the aperture time is the time it takes for the switch to fully ___ after the control switches from ___ A. Close, sample to hold B. Open, sample to hold C. Close, hold to sample

B. Open, sample to hold

Which of the following best describes statement 1 and 2? Statement A: Thyristors can be used in controlled heating, excitation systems of alternators, speed control of motors and HVDC. Statement B: A static variable system using thyristors is very commonly used in high voltage AC systems. A. Both statements are correct and B is correct explanation of A B. Both statements are correct but B is not a correct explanation of A C. One of the statement is wrong

B. Both statements are correct but B is not a correct explanation of A

In HVDC transmission lines A. both the stations operate as a converter B. one acts as a converter and other as an inverter C. both the stations operate as an inverter

B. one acts as a converter and other as an inverter

A static excitation system uses A. transformer and ac exciter B. transformer and dc exciter C. transformer and thyristors D. dc exciter and ac exciter

C. transformer and thyristors