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The product of the readings of an AC voltmeter and AC ammeter is called?
Apparent power
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What is the basic unit of electrical power?
Watt
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What is the term used to express the amount of electrical energy stored in an electrostatic field?
Joules
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What determines the strength of the magnetic field around a conductor?
The amount of current.
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What will produce a magnetic field?
A current flowing through a conductor.
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When induced currents produce expanding magnetic fields around conductors in a direction that opposes the original magnetic filed, this is known as?
Lenz's law
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Skin effect is the phenomenon where?
RF current flows in a thin layer of the conductor, closer to the surface, as frequency increases.
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Which of these will be most useful for insulation at UHF frequencies?
Mica
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Which of the 4 groups of metals listed below are the best low- resistance conductors?
Gold, silver, and copper
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What is the purpose of a bypass capacitor?
It removes alternating current by providing a low impedance path to ground.
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How would you calculate the total capacitanc of three capacitors in parallel?
Ct = C1+ C2+ C3
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What are the two most commonly- used specifications for a junction diode?
Maximum forward current and PIV (peak inverse voltage.)
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What are the two basic types of junction field- effect transistors?
N- channel and P- channel
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How does the input impedance of a field- effect transistor compare with that of a bipolar transistor?
An FET has high input impedance; a bipolar transistor has low input impedance.
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An AC ammeter indicates:
Effective (RMS) values of current
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*By what factor must the voltage of an AC circuit, as indicated on the scale of an AC voltmeter, be multiplied to obtain the peak voltage value?
1.414
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*What is the easiest voltage amplitude to measure by viewing a pure sine wave signal on an oscilloscope?
Peak- to- peak
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What is a sine wave?
A wave following the laws of the trigonometric tangent function.
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How many degrees are there in one complete sine wave cycle?
360 degrees.
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What type of wave is characterized by a rise time significantly faster than the fall time (or vise versa?)
Sawtooth wave
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What is the term used to identify an AC voltage that would cause the same heating in a resistor as a corresponding value of DC voltage?
Root mean square (RMS)
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Halving the cross- sectional area of a conductor will?
Double the resistance.
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How do you compute true power (power dissipated in the circuit) in a circuit where AC voltage and current are out of phase?
Multiply apparent power times the power factor.
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What value of series resistor would be needed to obtain a full scale deflection on a 50 microamp DC meter with an applied voltage of 200 volts DC?
4 megohms
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Which of the following Ohms Law formulas is incorrect?
I = R / E
- Correct formulas:
- R = E / I
- E = I * R
- I = E / R
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If a current of 2 amperes flows through a 50- ohm resistor, what is the voltage across the resistor?
100 volts
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What is the peak- to- peak RF voltage on the 50 ohm output of a 100 watt transmitter?
200 volts
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What is the maximum DC or RMS voltage that may be connected across a 20 watt, 2000 ohm resistor?
200 volts
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What is the maximun rated current- carrying capacity of a resistor marked "2000 ohms, 200 watts?"
0.316 amps
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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 plus or minus 0.1 ppm?
46.21 Hz
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The second harmonic of a 380 kHz frequency is:
760 kHz
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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 +/ - 10 ppm?
1565.20 Hz
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At 150 degrees, what is the amplitude of a sine- wave having a peak value of 5 volts?
+ 2.5 volts
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What is the equivalent to the root- mean- square value of an AC voltage?
The DC voltage causing the same heating in a given resistor as the RMS AC voltage of the same value.
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Determine the phase relationship between the two signals shown in Figure.
B is lagging A by 90 degrees.
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If a resistance to which a constant voltage is applied is halved, what power dissipation will result?
Double
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In a circuit where the AC voltage and current are out of phase, how can the true power be determined.
By multiplying the apparent power times the power factor.
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What does the power factor equal in an R- L circuit having a 30 degree phase angle between the voltage and the current?
0.866
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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.
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After two time constants, the capacitor in an RC circuit is discharged to what percentage of the starting voltage?
13.5%
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What is the time constant of a circuit having two 220- microfarad capacitors and two 1- megohm resistors all in parallel?
220 seconds
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What is the time constant of a circuit having a 220- microfarad capacitor and a 1- megohm resistor in parallel?
220 seconds
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What is the time constant of a circuit having two 220- microfarad capacitors and two 1- megohm resistors in series?
220 seconds
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What is the impedance of a network composed of a 0.1- microhenry inductor in series with a 20- ohm resistor, at 30 MHz? Specify your answer in rectangular coordinates.
20 +j19
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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
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In polar coordinates, what is the impedance of a network composed of a 400- ohm- reactance capacitor in series with a 300- ohm resistor?
500- ohm, / -53.1 degrees
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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
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Using the polar coordinate system, what visual representation would you get of a voltage in a sinewave circuit?
The plot shows the magnitude and phase angle.
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A 1- watt, 10 volt Zener diode with the following characteristics: Imin = 5mA; Imax = 95 mA; and Z = 8 ohms, is uesed as part of a voltage regulator in a 20- V power supply. Approximately what size current- limiting resistor would be used to set its bias to the midpoint of its operation range?
200 ohms
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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?
20%
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What is the conductance (G) of a circuit if 6 amperes of current flows when 12 volts DC is applied?
.50 Siemens (mhos) (6 is .50 of 12)
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What is the photoconductive effect?
The increased conductivity of an illuminated semiconductor junction.
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What is the description of an optoisolator?
An LED and a photosensitive device.
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What happens to the conducitivity of a photosensitive semiconductor junction when it is illuminated?
The junction resistance decreases.
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What factors determine the capacitance of a capacitor?
Distance between the plates and the dielectric constant of the material between the plates.
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In figure shown, which component (labeled 1 through 4) is used to provide a signal ground?
2
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What is the purpose of a coupling capacitor?
It blocks direct current and passes alternating current.
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A tranformer primary of 2250 turns connected to 120 VAC will develop what voltage across a 500- turn secondary?
26.7 volts
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A power transformer has a primary winding of 200 turns of 24# wire and a secondary winding consisting of 500 turns of the same size wire. When 20 volts are applied to the primary winding, the expected secondary voltage will be:
50 voltage
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What are the three terminals of an SCR?
Anode, cathode, and gate
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What circuit might contain a SCR?
A light- dimming circuit.
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What type of semiconductor diode varies its internal capacitance as the voltage applied to its terminals varies?
Varactor diode
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What is the approximate magnitude of the impedance of a parallel R- L- C circuit at resonance?
Approximately equal to the circuit resistance.
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How could voltage be greater across reactance's in series than the applied voltage?
Resonance
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What is the characteristic of the current flow within the parallel elements in a parallel R- L- C circuit at resonance?
Maximum
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What is the main advantage of using an op- amp audio filter over a passive LC audio filter?
Op- amps exhibit gain rather than insertion loss.
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Which of the following op- amp circuits is operated open- loop?
Comparator
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In the op- amp oscillator circuit shown in Figure, what would be the most noticeable effect if the capacitance of C were suddenly doubled?
Frequency would be lower
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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.
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What spectral impurity components might be generated by a phase- locked- loop synthesizer?
Broadband nosie
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What is the definition of a phase- locked loop (PLL) circuit?
A servo loop consisting of a phase detector, a low- pass filter and voltage- controlled oscillater.
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Which lamps would be lit in the circuit shown in Figure?
2, 3, 4, 7, and 8
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In Figure with a square wave input what would be the output?
3
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With a pure AC signal input to the circuit shown in Figure, what output wave form would you expect to see on an oscilloscope display?
2
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What is the voltage range considered to be valid logic low input in a TTL device operation at 5 volts?
Zero to 0.8 volts
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TTL inputs left open develop what logic state?
A high- logic state.
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What is a characteristic of an AND gate?
Produces a logic "1" as its output only if all inputs are logic "1"
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What is a characteristic of an NOR gate?
Produces a logic "0" at its output when the input is logic "1" and vice versa.
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What is a characteristic of an NOT gate?
Produces a logic "0" at its output when the input is logic "1" and vice versa.
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For the logic input levels shown in Figure, what are the logic levels of test A, B and C in this circuit?
A is low, B is high and C is high.
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In a positive- logic circuit, what level is used to represent a logic 1?
High level
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Given the input levels shown in Figure and assuming positive logic devices, what would the output be?
A is low, B is high and C is high.
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A flip- flop circuit is a binary logic element with how many stable states?
2
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How many bits of information can be stored in a single flip- flop circuit?
1
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An R- S flip- flop is capable of doing all of the following except:
Operate in toggle mode with R- S inputs with CLK initiated.
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What is an astable multivibrator?
A circuit that alternates between two unstable states.
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What is a monostable vibrator?
A circuit that can be switched momentarily to the opposite binary state and then returns after a set time to its original state.
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What is a bistable multivibrator circuit commonly named?
Flip- flop
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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?
RAM- Random Access Memory
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What is the name of the semiconductor IC that has a fixed pattern of digital data stored in its memory matrix?
ROM- Read - Only Memory
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What does the term "IO" mean within a microprocessor system?
Input- output
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In a microprocessor- controlled two- way radio, a "watchdog" timer
Verifies that the microprocessor is executing the program
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What portion of a microprocessor circuit is the pulse generator?
Clock
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What circuit interconnects the microprocessor with the memory and input/output system?
Data bus line
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What is the function of a decade counter digital IC?
Produce one output pulse for every ten input pulses.
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What integrated circuit device converts an analog signal to digital signal?
A D C (analog to digital converter)
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In binary numbers, how would you note the quantity TWO?
0010
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