3-1A1 The product of the readings of an AC voltmeter and AC ammeter is called:

A. Apparent power.

3-1A2 What is the basic unit of electrical power?

A. Joules.

3-1A4 What device is used to store electrical energy in an electrostatic field?

C. Capacitor.

3-1A5 What formula would determine the inductive reactance of a coil if frequency and coil inductance are known?

B. X_L = 2p f L

3-2A1 What determines the strength of the magnetic field around a conductor?

D. The amount of current.

3-2A2 What will produce a magnetic field?

C. A current flowing through a conductor.

3-2A3 When induced currents produce expanding magnetic fields around conductors in a direction that opposes the original magnetic field, this is known as:

A. Lenz’s law

3-2A4 The opposition to the creation of magnetic lines of force in a magnetic circuit is known as:

D. Reluctance.

3-2A5 What is meant by the term “back EMF”?

C. A voltage that opposes the applied EMF.

3-2A6 Permeability is defined as:

B. The ratio of magnetic flux density in a substance to the magnetizing force that produces it.

Key Topic 3: Materials

3-3A1 What metal is usually employed as a sacrificial anode for corrosion control purposes?

C. Zinc bar.

3-3A2 What is the relative dielectric constant for air?

A. 1

3-3A3 Which metal object may be least affected by galvanic corrosion when submerged in seawater?

D. Stainless steel propeller shaft.

3-3A4 Skin effect is the phenomenon where:

A. RF current flows in a thinner layer of the conductor, closer to the surface, as frequency increases.

3-3A5 Corrosion resulting from electric current flow between dissimilar metals is called:

D. Galvanic corrosion.

3-3A6 Which of these will be most useful for insulation at UHF frequencies?

B. Mica.

Key Topic 4: Resistance, Capacitance & Inductance

3-4A1 What formula would calculate the total inductance of inductors in series?

B. L_T = L₁ + L₂

3-4A2 Good conductors with minimum resistance have what type of electrons?

D. Many free electrons.

3-4A3 Which of the 4 groups of metals listed below are the best low-resistance conductors?

A. Gold, silver, and copper.

3-4A4 What is the purpose of a bypass capacitor?

C. It removes alternating current by providing a low impedance path to ground.

3-4A5 How would you calculate the total capacitance of three capacitors in parallel?

B. C_T = C₁ + C₂ + C₃.

3-4A6 How might you reduce the inductance of an antenna coil?

C. Reduce the number of turns.

Key Topic 5: Semi-conductors

3-5A1 What are the two most commonly-used specifications for a junction diode?

D. Maximum forward current and PIV (peak inverse voltage).

3-5A2 What limits the maximum forward current in a junction diode?

B. The junction temperature.

3-5A3 MOSFETs are manufactured with THIS protective device built into their gate to protect the device from static charges and excessive voltages:

C. Zener diode.

3-5A4 What are the two basic types of junction field-effect transistors?

A. N-channel and P-channel.

3-5A5 A common emitter amplifier has:

B. More voltage gain than a common collector.

3-5A6 How does the input impedance of a field-effect transistor compare with that of a bipolar transistor?

A. An FET has high input impedance; a bipolar transistor has low input impedance.

Key Topic 6: Electrical Measurements

3-6A1 An AC ammeter indicates:

B. Effective (RMS) values of current.

3-6A2 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?

C. 1.414

3-6A3 What is the RMS voltage at a common household electrical power outlet?

D. 117-V AC.

3-6A3 What is the RMS voltage at a common household electrical power outlet?

D. 117-V AC.

3-6A4 What is the easiest voltage amplitude to measure by viewing a pure sine wave signal on an oscilloscope?

A. Peak-to-peak.

3-6A5 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?

C. 0.9

3-6A6 What is the peak voltage at a common household electrical outlet?

D. 165.5 volts.

Key Topic 7: Waveforms

3-7A1 What is a sine wave?

B. 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.

3-7A2 How many degrees are there in one complete sine wave cycle?

D. 360 degrees.

3-7A3 What type of wave is made up of sine waves of the fundamental frequency and all the odd harmonics?

A. Square.

3-7A4 What is the description of a square wave?

D. A wave that abruptly changes back and forth between two voltage levels and stays at these levels for equal amounts of time.

3-7A5 What type of wave is made up of sine waves at the fundamental frequency and all the harmonics?

A. Sawtooth wave.

3-7A6 What type of wave is characterized by a rise time significantly faster than the fall time (or vice versa)?

C. Sawtooth wave.

Key Topic 8: Conduction

3-8A1 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?

C. Root mean square (RMS).

3-8A2 What happens to reactive power in a circuit that has both inductors and capacitors?

B. It alternates between magnetic and electric fields and is not dissipated.

3-8A3 Halving the cross-sectional area of a conductor will:

C. Double the resistance.

3-8A4 Which of the following groups is correct for listing common materials in order of descending conductivity?

A. Silver, copper, aluminum, iron, and lead.

3-8A5 How do you compute true power (power dissipated in the circuit) in a circuit where AC voltage and current are out of phase?

D. Multiply apparent power times the power factor.

3-8A6 Assuming a power source to have a fixed value of internal resistance, maximum power will be transferred to the load when:

3-16B1 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.

C. 20 +j19

3-16B2 In rectangular coordinates, what is the impedance of a network composed of a 0.1-microhenry inductor in series with a 30-ohm resistor, at 5 MHz?

D. 30 +j3

3-16B3 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?

A. 40 +j31400

3-16B4 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?

B. 200 + j188

3-16B5 In rectangular coordinates, what is the impedance of a network composed of a 0.01-microfarad capacitor in parallel with a 300-ohm resistor, at 50 kHz?

C. 159 - j150

3-16B6 In rectangular coordinates, what is the impedance of a network composed of a 0.001-microfarad capacitor in series with a 400-ohm resistor, at 500 kHz?

3-17B1 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.

D. 2490 ohms, /-51.5 degrees

3-17B2 In polar coordinates, what is the impedance of a network composed of a 100-ohm-reactance inductor in series with a 100-ohm resistor?

B. 141 ohms, /45 degrees

3-17B3 In polar coordinates, what is the impedance of a network composed of a 400-ohm-reactance capacitor in series with a 300-ohm resistor?

C. 500 ohms, /-53.1 degrees

3-17B4 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?

A. 500 ohms, /37 degrees

3-17B5 In polar coordinates, what is the impedance of a network comprised of a 400-ohm-reactance inductor in parallel with a 300-ohm resistor?

B. 240 ohms, /36.9 degrees

3-17B6 Using the polar coordinate system, what visual representation would you get of a voltage in a sinewave circuit?

D. The plot shows the magnitude and phase angle.

Key Topic 18: Calculations

3-18B1 What is the magnitude of the impedance of a series AC circuit having a resistance of 6 ohms, an inductive reactance of 17 ohms, and zero capacitive reactance?

C. 18 ohms.

3-18B2 A 1-watt, 10-volt Zener diode with the following characteristics: I_min. = 5 mA; I_max. = 95 mA; and Z = 8 ohms, is to be used 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 operating range?

B. 200 ohms.

3-18B3 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?

C. 20 %

3-18B4 What turns ratio does a transformer need in order to match a source impedance of 500 ohms to a load of 10 ohms?

A. 7.1 to 1.

3-18B5 Given a power supply with a full load voltage of 200 volts and a regulation of 25%, what is the no load voltage?

D. 250 volts.

3-18B6 What is the conductance (G) of a circuit if 6 amperes of current flows when 12 volts DC is applied?

B. 0.50 Siemens (mhos).

Subelement C – Components: 10 Key Topics, 10 Exam Questions, 2 Drawings

Key Topic 19: Photoconductive Devices

3-19C1 What happens to the conductivity of photoconductive material when light shines on it?

A. It increases.

3-19C2 What is the photoconductive effect?

B. The increased conductivity of an illuminated semiconductor junction.

3-19C3 What does the photoconductive effect in crystalline solids produce a noticeable change in?

D. The resistance of the solid.

3-19C4 What is the description of an optoisolator?

A. An LED and a photosensitive device.

3-19C5 What happens to the conductivity of a photosensitive semiconductor junction when it is illuminated?

B. The junction resistance decreases.

3-19C6 What is the description of an optocoupler?

C. An LED and a photosensitive device.

Key Topic 20: Capacitors

3-20C1 What factors determine the capacitance of a capacitor?

D. Distance between the plates and the dielectric constant of the material between the plates.

3-20C2 In Figure 3C4, if a small variable capacitor were installed in place of the dashed line, it would?

C. Decrease parasitic oscillations.

3-20C3 In Figure 3C4, which component (labeled 1 through 4) is used to provide a signal ground?

B. 2

3-20C4 In Figure 3C5, which capacitor (labeled 1 through 4) is being used as a bypass capacitor?

C. 3

3-20C5 In Figure 3C5, the 1 μF capacitor is connected to a potentiometer that is used to:

D. Adjust tone.

3-20C6 What is the purpose of a coupling capacitor?

3-21C1 A capacitor is sometimes placed in series with the primary of a power transformer to:

3-21C2 A transformer used to step up its input voltage must have:

B. More turns of wire on its secondary than on its primary.

3-21C3 A transformer primary of 2250 turns connected to 120 VAC will develop what voltage across a 500-turn secondary?

A. 26.7 volts.

3-21C4 What is the ratio of the output frequency to the input frequency of a single-phase full-wave rectifier?

C. 2:1.

3-21C5 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?

B. The 150 volt winding.

3-21C6 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:

D. 50 volts.

Key Topic 22: Voltage Regulators, Zener Diodes

3-22C1 In a linear electronic voltage regulator:

D. The conduction of a control element is varied in direct proportion to the line voltage or load current.

3-22C2 A switching electronic voltage regulator:

C. Switches the control device on or off, with the duty cycle proportional to the line or load conditions.

3-22C3 What device is usually used as a stable reference voltage in a linear voltage regulator?

A. Zener diode.

3-22C4 In a regulated power supply, what type of component will most likely be used to establish a reference voltage?

D. Zener Diode.

3-22C5 A three-terminal regulator:

C. Contains a voltage reference, error amplifier, sensing resistors and transistors, and a pass element.

3-22C6 What is the range of voltage ratings available in Zener diodes?

B. 2.4 volts to 200 volts and above.

Key Topic 23: SCRs, Triacs

3-23C1 How might two similar SCRs be connected to safely distribute the power load of a circuit?

C. In parallel, reverse polarity.

3-23C2 What are the three terminals of an SCR?

A. Anode, cathode, and gate.

3-23C3 Which of the following devices acts as two SCRs connected back to back, but facing in opposite directions and sharing a common gate?

D. TRIAC.

3-23C4 What is the transistor called that is fabricated as two complementary SCRs in parallel with a common gate terminal?

A. TRIAC.

3-23C5 What are the three terminals of a TRIAC?

D. Gate, anode 1, and anode 2.

3-23C6 What circuit might contain a SCR?

B. A light-dimming circuit.

Key Topic 24: Diodes

3-24C1 What is one common use for PIN diodes?

B. RF switch.

3-24C2 What is a common use of a hot-carrier diode?

D. VHF and UHF mixers and detectors.

3-24C3 Structurally, what are the two main categories of semiconductor diodes?

A. Junction and point contact.

3-24C4 What special type of diode is capable of both amplification and oscillation?

C. Tunnel diodes.

3-24C5 What type of semiconductor diode varies its internal capacitance as the voltage applied to its terminals varies?

B. Varactor diode.

3-24C6 What is the principal characteristic of a tunnel diode?

C. Negative resistance region.

Key Topic 25: Transistors-1

3-25C1 What is the meaning of the term “alpha” with regard to bipolar transistors? The change of:

3-25C2 What are the three terminals of a bipolar transistor?

B. Base, collector and emitter.

3-25C3 What is the meaning of the term “beta” with regard to bipolar transistors? The change of:

C. Collector current with respect to base current.

3-25C4 What are the elements of a unijunction transistor?

A. Base 1, base 2, and emitter.

3-25C5 The beta cutoff frequency of a bipolar transistor is the frequency at which:

B. Emitter current gain has decreased to 0.707 of maximum.

3-25C6 What does it mean for a transistor to be fully saturated?