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WorksheetsElement 3
Total questions: 116
Worksheet time: 58mins
1. The product of the readings of an AC voltmeter and AC ammeter is called:
Apparent power
True power
Power factor
Current power
1. What is the term for the out-of-phase power associated with inductors and capacitors?
Effective power
. True power.
Peak envelope power.
. Reactive power
1. Permeability is defined as:
A. The magnetic field created by a conductor wound on a laminated core and carrying current.
The ratio of magnetic flux density in a substance to the magnetizing force that produces it.
C. Polarized molecular alignment in a ferromagnetic material while under the influence of a magnetizing
force.
None of these.
1. The opposition to the creation of magnetic lines of force in a magnetic circuit is known as:
Eddy currents.
Hysteresis.
Permeability.
Reluctance
What is the basic unit of electrical power?
Ohm.
Watt.
Volt.
Ampere
1. What device is used to store electrical energy in an electrostatic field?
Battery.
Transformer.
Capacitor.
Inductor.
1. Corrosion resulting from electric current flow between dissimilar metals is called:
Electrolysis.
Stray current corrosion.
Oxygen starvation corrosion.
Galvanic corrosion.
1. What is the relative dielectric constant for air?
1
2
4
0
1. Good conductors with minimum resistance have what type of electrons?
Few free electrons.
. No electrons.
Some free electrons.
Many free electrons.
1. How would you calculate the total capacitance of three capacitors in parallel?
CT = C1 + C2 / C1 - C2 + C3.
. CT = C1 + C2 + C3.
CT = C1 + C2 / C1 x C2 + C3.
CT = 1 / C1+1 / C2 + 1 / C3
1. Which of the 4 groups of metals listed below are the best low-resistance conductors?
Gold, silver, and copper.
Stainless steel, bronze, and lead.
Iron, lead, and nickel.
Bronze, zinc, and manganese.
1. MOSFETs are manufactured with THIS protective device built into their gate to protect the device
from static charges and excessive voltages:
Schottky diode
Metal oxide varistor (MOV).
Zener diode.
Tunnel diode.
1. How does the input impedance of a field-effect transistor compare with that of a bipolar transistor?¿Cómo se compara la impedancia de entrada de un transistor de efecto de campo con la de un transistor bipolar
An FET has high input impedance; a bipolar transistor has low input impedance.
One cannot compare input impedance without first knowing the supply voltage.
An FET has low input impedance; a bipolar transistor has high input impedance.
The input impedance of FETs and bipolar transistors is the same.
1. By what factor must the voltage measured in an AC circuit, as indicated on the scale of an AC
voltmeter, be multiplied to obtain the average voltage value?
0.707
1.414
0.9
3.14
1. What is the easiest voltage amplitude to measure by viewing a pure sine wave signal on an
oscilloscope?
Peak-to-peak.
RMS.
Average.
DC.
1. What type of wave is made up of sine waves of the fundamental frequency and all the odd
harmonics?
Square.
Sine.
Cosine.
Tangent.
What is a sine wave?
A constant-voltage, varying-current wave.
A wave whose amplitude at any given instant can be represented by the projection of a point on a
wheel rotating at a uniform speed.
A wave following the laws of the trigonometric tangent function.
A wave whose polarity changes in a random manner.
1. How many degrees are there in one complete sine wave cycle?
90 degrees.
270 degrees.
180 degrees.
360 degrees.
1. How do you compute true power (power dissipated in the circuit) in a circuit where AC voltage and current are out of phase?
Multiply RMS voltage times RMS current.
Subtract apparent power from the power factor.
Divide apparent power by the power factor.
Multiply apparent power times the power factor.
Halving the cross-sectional area of a conductor will:
Not affect the resistance.
Quarter the resistance.
Double the resistance.
Halve the resistance.
What is the description of a square wave?
A wave with only 300 degrees in one cycle.
A wave whose periodic function is always negative.
A wave whose periodic function is always positive.
A wave that abruptly changes back and forth between two voltage levels and stays at these levels for equal amounts of time.
A relay coil has 500 ohms resistance, and operates on 125 mA. What value of resistance should be
connected in series with it to operate from 110 V DC?
150 ohms.
220 ohms.
380 ohms.
470 ohms.
1. Which of the following Ohms Law formulas is incorrect
I = E / R
I = R / E
E = I x R
R = E / I
In Figure 3B1, what is the voltage drop across R1? VER FIGURA CUESTIONARIO
9 volts
7 volts
5 volts
3 volts
1. What is the maximum DC or RMS voltage that may be connected across a 20 watt, 2000 ohm
resistor?
10 volts.
200 volts.
100 volts.
10,000 volts.
1. What is the most the actual transmit frequency could differ from a reading of 462,100,000 Hertz on a frequency counter with a time base accuracy of ± 0.1 ppm?
46.21 Hz.
0.1 MHz.
462.1 Hz.
0.2 MHz.
1. What is the most the actual transmitter frequency could differ from a reading of 156,520,000 hertz on a frequency counter with a time base accuracy of ± 1.0 ppm?
165.2 Hz.
15.652 kHz.
156.52 Hz.
1.4652 MHz.
What is the equivalent to the root-mean-square value of an AC voltage?
AC voltage is the square root of the average AC value.
B. The DC voltage causing the same heating in a given resistor at the peak AC voltage.
The DC voltage causing the same heating in a given resistor at the peak AC voltage.
The AC voltage found by taking the square of the average value of the peak AC voltage.
The DC voltage causing the same heating in a given resistor as the RMS AC voltage of the same value.
What is the RMS value of a 340-volt peak-to-peak pure sine wave?
170 volts AC.
. 120 volts AC.
240 volts AC.
350 volts AC.
What does the power factor equal in an R-L circuit having a 60 degree phase angle between the
voltage and the current?
0.414
0.866
0.5
1.73
746 watts, corresponding to the lifting of 550 pounds at the rate of one-foot-per-second, is the
equivalent of how much horsepower?
One-quarter horsepower.
One-half horsepower.
Three-quarters horsepower.
One horsepower.
If a resistance to which a constant voltage is applied is halved, what power dissipation will result?
Double.
Halved.
Quadruple.
Remain the same.
After two time constants, the capacitor in an RC circuit is discharged to what percentage of the
starting voltage?
86.5 %
13.5 %
63.2 %
36.8 %
What is the meaning of the term “time constant of an RC circuit”? The time required to charge the capacitor in the circuit to:
23.7% of the supply voltage.
36.8% of the supply voltage.
57.3% of the supply voltage.
63.2% of the supply voltage.
What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm
resistors all in parallel?
22 seconds.
44 seconds.
440 seconds.
220 seconds.
What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm
resistors all in series?
220 seconds.
55 seconds.
110 seconds.
440 seconds.
What is the term for the time required for the current in an RL circuit to build up to 63.2% of the
maximum value?
One time constant
An exponential period of one.
A time factor of one.
One exponential rate.
. In rectangular coordinates, what is the impedance of a network composed of a 1.0-millihenry
inductor in series with a 200-ohm resistor, at 30 kHz?
200 - j188
200 + j188
188 + j200
188 - j200
In rectangular coordinates, what is the impedance of a network composed of a 10-microhenry
inductor in series with a 40-ohm resistor, at 500 MHz?
40 +j31400
40 -j31400
31400 +j40
31400 -j40
. What is the impedance of a network composed of a 100-picofarad capacitor in parallel with a 4000-
ohm resistor, at 500 KHz? Specify your answer in polar coordinates.
2490 ohms, /51.5 degrees
4000 ohms, /38.5 degrees
5112 ohms, /-38.5 degrees
2490 ohms, /-51.5 degrees
In polar coordinates, what is the impedance of a network composed of a 400-ohm-reactance
capacitor in series with a 300-ohm resistor?
240 ohms, /36.9 degrees
240 ohms, /-36.9 degrees
500 ohms, /-53.1 degrees
500 ohms, /53.1 degrees
. In polar coordinates, what is the impedance of a network composed of a 300-ohm-reactance
capacitor, a 600-ohm-reactance inductor, and a 400-ohm resistor, all connected in series?
500 ohms, /37 degrees
400 ohms, /27 degrees
300 ohms, /17 degrees
200 ohms, /10 degrees
Given a power supply with a no load voltage of 12 volts and a full load voltage of 10 volts, what is
the percentage of voltage regulation?
17 %
80 %
20 %
83 %
. Given a power supply with a full load voltage of 200 volts and a regulation of 25%, what is the no load voltage?
150 volts.
160 volts.
240 volts.
250 volts.
. What is the photoconductive effect?
The conversion of photon energy to electromotive energy.
The increased conductivity of an illuminated semiconductor junction.
The conversion of electromotive energy to photon energy.
The decreased conductivity of an illuminated semiconductor junction
What is the description of an optoisolator?
An LED and a photosensitive device.
A P-N junction that develops an excess positive charge when exposed to light.
An LED and a capacitor.
n LED and a lithium battery cell.
What factors determine the capacitance of a capacitor?
Voltage on the plates and distance between the plates.
Voltage on the plates and the dielectric constant of the material between the plates.
Amount of charge on the plates and the dielectric constant of the material between the plates.
Distance between the plates and the dielectric constant of the material between the plates.
. In Figure 3C5, which capacitor (labeled 1 through 4) is being used as a bypass capacitor?
1
2
3
4
. What is the ratio of the output frequency to the input frequency of a single-phase full-wave
rectifier?
1:1.
1:2.
2:1
None of these.
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?
The 12.6 volt winding.
The 150 volt winding.
The 5.0 volt winding.
All will have equal resistance values.
A switching electronic voltage regulator:
Varies the conduction of a control element in direct proportion to the line voltage or load current.
Provides more than one output voltage.
Switches the control device on or off, with the duty cycle proportional to the line or load conditions.
Gives a ramp voltage at its output.
A three-terminal regulator:
Supplies three voltages with variable current.
Supplies three voltages at a constant current.
Contains a voltage reference, error amplifier, sensing resistors and transistors, and a pass element.
Contains three error amplifiers and sensing transistors.
What device is usually used as a stable reference voltage in a linear voltage regulator?
Zener diode.
Tunnel diode.
SCR.
Varactor diode.
What is the transistor called that is fabricated as two complementary SCRs in parallel with a
common gate terminal?
TRIAC.
Bilateral SCR.
Unijunction transistor.
Field effect transistor.
What are the three terminals of an SCR?
Anode, cathode, and gate.
Gate, source, and sink.
Base, collector, and emitter.
Gate, base 1, and base 2.
. What is one common use for PIN diodes?
Constant current source.
RF switch.
Constant voltage source.
RF rectifier.
What type of semiconductor diode varies its internal capacitance as the voltage applied to its
terminals varies?
. Tunnel diode.
Varactor diode.
Silicon-controlled rectifier.
Zener diode.
What are the elements of a unijunction transistor?
Base 1, base 2, and emitter.
Gate, cathode, and anode.
Gate, base 1, and base 2.
Gate, source, and sink.
. What are the three terminals of a bipolar transistor?
Cathode, plate and grid.
Base, collector and emitter.
Gate, source and sink.
Input, output and ground.
A common base amplifier has:
More current gain than common emitter or common collector.
More voltage gain than common emitter or common collector.
More power gain than common emitter or common collector.
Highest input impedance of the three amplifier configurations.
An emitter-follower amplifier has:
More voltage gain than common emitter or common base.
More power gain than common emitter or common base.
Lowest input impedance of the three amplifier configurations.
More current gain than common emitter or common base.
. What determines the visible color radiated by an LED junction?
The color of a lens in an eyepiece.
The amount of voltage across the device.
The amount of current through the device.
The materials used to construct the device.
What would be the maximum current to safely illuminate a LED?
1 amp.
1 microamp.
500 milliamps.
20 mA.
An LED facing a photodiode in a light-tight enclosure is commonly known as a/an:
Optoisolator.
Seven segment LED.
Optointerrupter.
Infra-red (IR) detector.
What circuit component must be connected in series to protect an LED?
Bypass capacitor to ground.
Electrolytic capacitor.
Series resistor.
Shunt coil in series.
What is the piezoelectric effect?
Mechanical vibration of a crystal by the application of a voltage.
Mechanical deformation of a crystal by the application of a magnetic field.
The generation of electrical energy by the application of light.
Reversed conduction states when a P-N junction is exposed to light.
What do the initials CMOS stand for?
Common mode oscillating system.
Complementary mica-oxide silicon.
Complementary metal-oxide semiconductor.
Complementary metal-oxide substrate
. An electrical relay is a:
Current limiting device.
Device used for supplying 3 or more voltages to a circuit.
Component used mainly with HF audio amplifiers.
Remotely controlled switching device.
. What is the characteristic of the current flow in a series R-L-C circuit at resonance?
Maximum.
Minimum.
DC.
Zero.
69. What is the approximate magnitude of the impedance of a series R-L-C circuit at resonance?
High, as compared to the circuit resistance.
Approximately equal to the circuit resistance.
Approximately equal to XL.
Approximately equal to XC.
Which of the following op-amp circuits is operated open-loop?
.Non-inverting amp.
Inverting amp.
Active filter.
Comparator.
What are the characteristics of an inverting operational amplifier (op-amp) circuit?
It has input and output signals in phase.
Input and output signals are 90 degrees out of phase.
It has input and output signals 180 degrees out of phase.
Input impedance is low while the output impedance is high.
. What frequency synthesizer circuit uses a phase comparator, look-up table, digital-to-analog
converter, and a low-pass antialias filter?
A direct digital synthesizer.
Phase-locked-loop synthesizer.
A diode-switching matrix synthesizer.
A hybrid synthesizer.
What spectral impurity components might be generated by a phase-locked-loop synthesizer?
Spurs at discrete frequencies.
Random spurs which gradually drift up in frequency.
Broadband noise
Digital conversion noise.
. Which lamps would be lit in the circuit shown in Figure 3D8?
2, 3, 4, 5 and 6.
5, 6, 8 and 9.
2, 3, 4, 7 and 8.
1, 3, 5, 7 and 8.
In Figure 3D10 with a square wave input what would be the output?
1
2
3
4
. Which of the following instruments would be best for checking a TTL logic circuit?
VOM.
DMM.
Continuity tester.
Logic probe.
Which of the following logic gates will provide an active high out when both inputs are active high?
NAND.
NOR.
AND.
XOR.
. For the logic input levels given in Figure 3E13, what are the logic levels of test points A, B and C in this circuit? (Assume positive logic.)
A is low, B is low and C is high.
A is low, B is high and C is low.
A is high, B is high and C is high.
A is high, B is low and C is low.
How many bits of information can be stored in a single flip-flop circuit?
1
2
3
4
What is the voltage range considered to be valid logic low input in a TTL device operating at 5
volts?
2.0 to 5.5 volts.
-2.0 to -5.5 volts.
Zero to 0.8 volts.
5.2 to 34.8 volts.
. What is a characteristic of a NAND gate?
Produces a logic “0” at its output only when all inputs are logic “0”.
Produces a logic “1” at its output only when all inputs are logic “1”.
Produces a logic “0” at its output if some but not all of its inputs are logic “1”.
Produces a logic “0” at its output only when all inputs are logic “1”.
In a positive-logic circuit, what level is used to represent a logic 1?
High level
Low level
Positive-transition level
Negative-transition level
How many flip-flops are required to divide a signal frequency by 4?
1
4
8
2
What do the initials TTL stand for?
Resistor-transistor logic.
Transistor-transistor logic.
Diode-transistor logic
Emitter-coupled logic.
. What is a bistable multivibrator circuit?
Flip-flop.
AND gate.
OR gate.
Clock.
What is the name of the random-accessed semiconductor memory IC that must be refreshed
periodically to maintain reliable data storage in its memory matrix?
ROM – Read-Only Memory.
DRAM – Dynamic Random-Access Memory.
PROM – Programmable Read-Only Memory.
PRAM – Programmable Random-Access Memory.
In a microprocessor-controlled two-way radio, a “watchdog” timer:
Verifies that the microprocessor is executing the program.
Assures that the transmission is exactly on frequency.
Prevents the transmitter from exceeding allowed power out.
Connects to the system RADAR presentation.
What integrated circuit device converts digital signals to analog signals?
ADC
DCC
CDC
DAC
. What is an astable multivibrator?
A circuit that alternates between two stable states.
A circuit that alternates between a stable state and an unstable state.
A circuit set to block either a 0 pulse or a 1 pulse and pass the other.
A circuit that alternates between two unstable states.
What is the name of the semiconductor memory IC whose digital data can be written or read, and whose memory word address can be accessed randomly?
ROM – Read-Only Memory.
PROM – Programmable Read-Only Memory.
RAM – Random-Access Memory.
EPROM – Electrically Programmable Read-Only Memory.
. Which of the following is not part of a MCU processor?
RAM
ROM
I/O
Voltage Regulator
. What circuit interconnects the microprocessor with the memory and input/output system?
Control logic bus.
PLL line.
Data bus line.
Directional coupler
. What is the purpose of a prescaler circuit?
Converts the output of a JK flip-flop to that of an RS flip-flop.
Multiplies an HF signal so a low-frequency counter can display the operating frequency.
Prevents oscillation in a low frequency counter circuit.
Divides an HF signal so that a low-frequency counter can display the operating frequency.
What is the definition of the term “receiver desensitizing”?
A burst of noise when the squelch is set too low.
A reduction in receiver sensitivity because of a strong signal on a nearby frequency.
A burst of noise when the squelch is set too high.
A reduction in receiver sensitivity when the AF gain control is turned down.
. How can selectivity be achieved in the front-end circuitry of a communications receiver?
By using an audio filter.
By using an additional RF amplifier stage
By using an additional IF amplifier stage.
By using a preselector.
. Which type of oscillator circuit is commonly used in a VFO (variable frequency oscillator)?
Colpitts.
Pierce.
Hartley.
Negative feedback.
3-44F6 What might occur in a receiver if excessive amounts of signal energy overdrive the mixer circuit?
Automatic limiting occurs.
Mixer blanking occurs.
Spurious mixer products are generated.
The mixer circuit becomes unstable and drifts.
What is meant by the term noise figure of a communications receiver?
The level of noise entering the receiver from the antenna.
The relative strength of a received signal 3 kHz removed from the carrier frequency.
The level of noise generated in the front end and succeeding stages of a receiver.
The ability of a receiver to reject unwanted signals at frequencies close to the desired one.
What is the limiting condition for sensitivity in a communications receiver?
The noise floor of the receiver.
The power supply output ripple.
The two-tone intermodulation distortion.
The input impedance to the detector.
What is the primary purpose of an RF amplifier in a receiver?
To provide most of the receiver gain.
To vary the receiver image rejection by utilizing the AGC.
To improve the receiver’s noise figure.
To develop the AGC voltage.
What is the advantage of a GaAsFET preamplifier in a modern VHF radio receiver?
Increased selectivity and flat gain.
Low gain but high selectivity.
. High gain and low noise floor.
High gain with high noise floor.
What is the oscillator stage called in a frequency synthesizer?
VCO.
Divider.
Phase detector.
Reference standard.
What are the principal frequencies that appear at the output of a mixer circuit?.
Two and four times the original frequency.
The sum, difference and square root of the input frequencies.
The original frequencies and the sum and difference frequencies.
1.414 and 0.707 times the input frequency.
How should the filter bandwidth of a receiver IF section compare with the bandwidth of a received signal?
Slightly greater than the received-signal bandwidth.
Approximately half the received-signal bandwidth.
Approximately two times the received-signal bandwidth.
Approximately four times the received-signal bandwidth.
What is the primary purpose of the final IF amplifier stage in a receiver?
Dynamic response.
Gain.
Noise figure performance.
Bypass undesired signals.
. What is an m-derived filter?
A filter whose input impedance varies widely over the design bandwidth.
A filter whose product of the series- and shunt-element impedances is a constant for all frequencies.
A filter whose schematic shape is the letter “M”.
A filter that uses a trap to attenuate undesired frequencies too near cutoff for a constant-k filter.
In a CTCSS controlled FM receiver, the CTCSS tone is filtered out after the:
. IF stage but before the mixer.
Mixer but before the IF.
IF but before the discriminator.
Discriminator but before the audio section.
What makes a Digital Coded Squelch work?
Noise.
Tones.
Absence of noise.
Digital codes.
Pulse type interference to automobile radio receivers that appears related to the speed of the engine can often be reduced by:
. Installing resistances in series with spark plug wires.
Using heavy conductors between the starting battery and the starting motor.
Connecting resistances in series with the battery.
Grounding the negative side of the battery.
What is the image frequency if the normal channel is 151.000 MHz, the IF is operating at 11.000
MHz, and the LO is at 140.000 MHz?
131.000 MHz.
129.000 MHz.
162.000 MHz.
150.000 MHz.
What degree of selectivity is desirable in the IF circuitry of a wideband FM phone receiver?
1 kHz.
2.4 KHZ
4.2 kHz.
15 kHz.
A receiver selectivity of 2.4 kHz in the IF circuitry is optimum for what type of signals?
CW.
Double-sideband AM voice.
SSB voice.
FSK RTTY.
What are the distinguishing features of a Chebyshev filter?
It has a maximally flat response over its passband.
It only requires inductors.
It allows ripple in the passband.
A filter whose product of the series- and shunt-element impedances is a constant for all frequencies.
A good crystal band-pass filter for a single-sideband phone would be?
5 KHz.
2.1 KHz.
500 Hz.
15 KHz.
What are the distinguishing features of a Butterworth filter?
A filter whose product of the series- and shunt-element impedances is a constant for all frequencies.
It only requires capacitors
It has a maximally flat response over its passband.
It requires only inductors.
