# Electrical Principles

E5A01 (A)What can cause the voltage across reactances in series to be larger than the voltage applied to them?

A. Resonance

E5A02 (C) What is resonance in an electrical circuit?

C. The frequency at which capacitive reactance equals inductive reactance

E5A03 (B)What are the conditions for resonance to occur in an electrical circuit?

B. Inductive and capacitive reactances are equal

E5A04 (D)When the inductive reactance of an electrical circuit equals its capacitive reactance, what is this condition called?

D. Resonance

E5A05 (D)What is the magnitude of the impedance of a series R-L-C circuit at resonance?

D. Approximately equal to circuit resistance

E5A06 (A)What is the magnitude of the impedance of a circuit with a resistor, an inductor and a capacitor all in parallel, at resonance?

A. Approximately equal to circuit resistance

E5A07 (B)What is the magnitude of the current at the input of a series R-L-C circuit at resonance?

B. It is at a maximum

E5A08 (B)What is the magnitude of the circulating current within the components of a parallel L-C circuit at resonance?

B. It is at a maximum

E5A09 (A)What is the magnitude of the current at the input of a parallel R-L-C circuit at resonance?

A. It is at a minimum

E5A10 (C) What is the relationship between the current through a resonant circuit and the voltage across the circuit?

C. The voltage and current are in phase

E5A11 (C) What is the relationship between the current into (or out of) a parallel resonant circuit and the voltage across the circuit?

C. The voltage and current are in phase

E5A12 (A)What is the half-power bandwidth of a parallel resonant circuit that has a resonant frequency of 1.8 MHz and a Q of 95?

A. 18.9 kHz

E5A13 (C) What is the half-power bandwidth of a parallel resonant circuit that has a resonant frequency of 7.1 MHz and a Q of 150?

C. 47.3 kHz

E5A14 (A)What is the half-power bandwidth of a parallel resonant circuit that has a resonant frequency of 14.25 MHz and a Q of 150?

A. 95 kHz

E5A15 (D)What is the half-power bandwidth of a parallel resonant circuit that has a resonant frequency of 21.15 MHz and a Q of 95?

D. 222.6 kHz

E5A16 (C) What is the half-power bandwidth of a parallel resonant circuit that has a resonant frequency of 3.7 MHz and a Q of 118?

C. 31.4 kHz

E5A17 (C) What is the half-power bandwidth of a parallel resonant circuit that has a resonant frequency of 14.25 MHz and a Q of 187?

C. 76.2 kHz

E5A18 (C) What is the resonant frequency of a series RLC circuit if R is 47 ohms, L is 50 microhenrys and C is 40 picofarads?

C. 3.56 MHz

E5A19 (B)What is the resonant frequency of a series RLC circuit if R is 47 ohms, L is 40 microhenrys and C is 200 picofarads?

B. 1.78 MHz

E5A20 (D)What is the resonant frequency of a series RLC circuit if R is 47 ohms, L is 50 microhenrys and C is 10 picofarads?

D. 7.12 MHz

E5A21 (A)What is the resonant frequency of a series RLC circuit if R is 47 ohms, L is 25 microhenrys and C is 10 picofarads?

A. 10.1 MHz

E5A22 (B)What is the resonant frequency of a series RLC circuit if R is 47 ohms, L is 3 microhenrys and C is 40 picofarads?

B. 14.5 MHz

E5A23 (D)What is the resonant frequency of a series RLC circuit if R is 47 ohms, L is 4 microhenrys and C is 20 picofarads?

D. 17.8 MHz

E5A24 (C) What is the resonant frequency of a series RLC circuit if R is 47 ohms, L is 8 microhenrys and C is 7 picofarads?

C. 21.3 MHz

E5A25 (A)What is the resonant frequency of a series RLC circuit if R is 47 ohms, L is 3 microhenrys and C is 15 picofarads?

A. 23.7 MHz

E5B01(B)What is the term for the time required for the capacitor in an RC circuit to be charged to 63.2% of the supply voltage?

B. One time constant

E5B02(A)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?

A. One time constant

E5B03 (D)What is the term for the time it takes for a charged capacitor in an RC circuit to discharge to 36.8% of its initial value of stored charge?

D. One time constant

E5B04 (C) The capacitor in an RC circuit is charged to what percentage of the supply voltage after two time constants?

C. 86.5%

E5B05 (D)The capacitor in an RC circuit is discharged to what percentage of the starting voltage after two time constants?

D. 13.5%

E5B06 (A)What is the time constant of a circuit having two 100-microfarad capacitors and two 470-kilohm resistors all in series?

A. 47 seconds

E5B07 (D)What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors all in parallel?

D. 220 seconds

E5B08 (C)What is the time constant of a circuit having a 220-microfarad capacitor in series with a 470-kilohm resistor?

C. 103 seconds

E5B09 (A)How long does it take for an initial charge of 20 V DC to decrease to 7.36 V DC in a 0.01-microfarad capacitor when a 2-megohm resistor is connected across it?

A. 0.02 seconds

E5B10 (B)How long does it take for an initial charge of 20 V DC to decrease to 0.37 V DC in a 0.01-microfarad capacitor when a 2-megohm resistor is connected across it?

B. 0.08 seconds

E5B11 (C) How long does it take for an initial charge of 800 V DC to decrease to 294 V DC in a 450-microfarad capacitor when a 1-megohm resistor is connected across it?

C. 450 seconds

E5C01 (A)What type of graph can be used to calculate impedance along transmission lines?

A. A Smith chart

E5C02 (B)What type of coordinate system is used in a Smith chart?

B. Resistance circles and reactance arcs

E5C03 (C) What type of calculations can be performed using a Smith chart?

C. Impedance and SWR values in transmission lines

E5C04 (C) What are the two families of circles that make up a Smith chart?

C. Resistance and reactance

E5C05 (A)What type of chart is shown in Figure E5-1?

A. Smith chart

E5C06 (B)On the Smith chart shown in Figure E5-1, what is the name for the large outer circle bounding the coordinate portion of the chart?

B. Reactance axis

E5C07 (D)On the Smith chart shown in Figure E5-1, what is the only straight line shown?

D. The resistance axis

E5C08 (C) What is the process of normalizing with regard to a Smith chart?

C. Reassigning impedance values with regard to the prime center

E5C09 (A)What is the third family of circles, which are added to a Smith chart during the process of solving problems?

A. Standing-wave ratio circles

E5C10 (A)In rectangular coordinates, what is the impedance of a network comprised of a 10-microhenry inductor in series with a 40-ohm resistor at 500 MHz?

A. 40 + j31,400

E5C11 (C)In polar coordinates, what is the impedance of a network comprised of a 100-picofarad capacitor in parallel with a 4,000-ohm resistor at 500 kHz?

C. 2490 ohms, /__-51.5_degrees__

E5C12 (D)Which point on Figure E5-2 best represents the impedance of a series circuit consisting of a 300-ohm resistor, a 0.64-microhenry inductor and a 85-picofarad capacitor at 24.900 MHz?

D. Point 8

E5C13 (D)What are the curved lines on a Smith chart?

D. Portions of reactance circles

E5C14 (B)How are the wavelength scales on a Smith chart calibrated?

B. In portions of transmission line electrical wavelength

E5D01 (A)What is the phase angle between the voltage across and the current through a series R-L-C circuit if XC is 25 ohms, R is 100 ohms, and XL is 100 ohms?

A. 36.9 degrees with the voltage leading the current

E5D02 (C) What is the phase angle between the voltage across and the current through a series R-L-C circuit if XC is 500 ohms, R is 1 kilohm, and XL is 250 ohms?

C. 14.0 degrees with the voltage lagging the current

E5D03 (D)What is the phase angle between the voltage across and the current through a series R-L-C circuit if XC is 50 ohms, R is 100 ohms, and XL is 25 ohms?

D. 14 degrees with the voltage lagging the current

E5D04 (A)What is the phase angle between the voltage across and the current through a series R-L-C circuit if XC is 100 ohms, R is 100 ohms, and XL is 75 ohms?

A. 14 degrees with the voltage lagging the current

E5D05 (D)What is the phase angle between the voltage across and the current through a series R-L-C circuit if XC is 50 ohms, R is 100 ohms, and XL is 75 ohms?

D. 14 degrees with the voltage leading the current

E5D06 (D)What is the relationship between the current through and the voltage across a capacitor?

D. Current leads voltage by 90 degrees

E5D07 (A)What is the relationship between the current through an inductor and the voltage across an inductor?

A. Voltage leads current by 90 degrees

E5D08 (B)What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 25 ohms, R is 100 ohms, and XL is 50 ohms?

B. 14 degrees with the voltage leading the current

E5D09 (B)What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 75 ohms, R is 100 ohms, and XL is 100 ohms?

B. 14 degrees with the voltage leading the current

E5D10 (C) What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 75 ohms, R is 100 ohms, and XL is 50 ohms?

C. 14 degrees with the voltage lagging the current

E5D11 (D)What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 250 ohms, R is 1 kilohm, and XL is 500 ohms?

D. 14.04 degrees with the voltage leading the current

E5E01 (B)In polar coordinates, what is the impedance of a network comprised of a 100-ohm-reactance inductor in series with a 100-ohm resistor?

B. 141 ohms, /__45_degrees__

E5E02 (D)In polar coordinates, what is the impedance of a network comprised of a 100-ohm-reactance inductor, a 100-ohm-reactance capacitor, and a 100-ohm resistor all connected in series?

D. 100 ohms, /__0_degrees__

E5E03 (A)In polar coordinates, what is the impedance of a network comprised 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__

E5E04 (D)In polar coordinates, what is the impedance of a network comprised of a 400-ohm-reactance capacitor in series with a 300-ohm resistor?

D. 500 ohms, /__-53.1_degrees__

E5E05 (A)In polar coordinates, what is the impedance of a network comprised of a 400-ohm-reactance inductor in parallel with a 300-ohm resistor?

A. 240 ohms, /__36.9_degrees__

E5E06 (D)In polar coordinates, what is the impedance of a network comprised of a 100-ohm-reactance capacitor in series with a 100-ohm resistor?

D. 141 ohms, /__-45_degrees__

E5E07 (C) In polar coordinates, what is the impedance of a network comprised of a 100-ohm-reactance capacitor in parallel with a 100-ohm resistor?

C. 71 ohms, /__-45_degrees__

E5E08 (B)In polar coordinates, what is the impedance of a network comprised of a 300-ohm-reactance inductor in series with a 400-ohm resistor?

B. 500 ohms, /__37_degrees__

E5E09 (A)When using rectangular coordinates to graph the impedance of a circuit, what does the horizontal axis represent?

A. The voltage or current associated with the resistive component

E5E10 (B)When using rectangular coordinates to graph the impedance of a circuit, what does the vertical axis represent?

B. The voltage or current associated with the reactive component

E5E11 (C) What do the two numbers represent that are used to define a point on a graph using rectangular coordinates?

C. The coordinate values along the horizontal and vertical axes

E5E12 (D)If you plot the impedance of a circuit using the rectangular coordinate system and find the impedance point falls on the right side of the graph on the horizontal line, what do you know about the circuit?

D. It is equivalent to a pure resistance

E5E13 (B)Why would you plot the impedance of a circuit using the polar coordinate system?

B. To give a visual representation of the phase angle

E5E14 (D)What coordinate system can be used to display the resistive, inductive, and/or capacitive reactance components of an impedance?

D. Rectangular

E5E15 (D)What coordinate system can be used to display the phase angle of a circuit containing resistance, inductive and/or capacitive reactance?

D. Polar

E5E16 (A)In polar coordinates, what is the impedance of a circuit of 100 -j100 ohms impedance?

A. 141 ohms, /__-45_degrees__

E5E17 (B)In polar coordinates, what is the impedance of a circuit that has an admittance of 7.09 millisiemens at 45 degrees?

B. 141 ohms, /__-45_degrees__

E5E18 (C) In rectangular coordinates, what is the impedance of a circuit that has an admittance of 5 millisiemens at -30 degrees?

C. 173 + j100 ohms

E5E19 (A)In rectangular coordinates, what is the admittance of a circuit that has an impedance of 240 ohms at 36.9 degrees?

A. 3.33 x 10(-3) - j2.50 x 10(-3) siemens

E5E20 (B)In polar coordinates, what is the impedance of a series circuit consisting of a resistance of 4 ohms, an inductive reactance of 4 ohms, and a capacitive reactance of 1 ohm?

B. 5 ohms, /__37_degrees__

E5E21 (B)Which point on Figure E5-2 best represents the impedance of a series circuit consisting of a 400 ohm resistor and a 38 picofarad capacitor at 14 MHz?

B. Point 4

E5E22 (B)Which point in Figure E5-2 best represents the impedance of a series circuit consisting of a 300 ohm resistor and an 18 microhenry inductor at 3.505 MHz?

B. Point 3

E5E23 (A)Which point on Figure E5-2 best represents the impedance of a series circuit consisting of a 300 ohm resistor and a 19 picofarad capacitor at 21.200 MHz?

A. Point 1

E5F01 (A)What is the result of skin effect?

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

E5F02 (C) What effect causes most of an RF current to flow along the surface of a conductor?

C. Skin effect

E5F03 (A)Where does almost all RF current flow in a conductor?

A. Along the surface of the conductor

E5F04 (D)Why does most of an RF current flow near the surface of a conductor?

D. Because of skin effect

E5F05 (C) Why is the resistance of a conductor different for RF currents than for direct currents?

C. Because of skin effect

E5F06 (C) What device is used to store electrical energy in an electrostatic field?

C. A capacitor

E5F07 (B)What unit measures electrical energy stored in an electrostatic field?

B. Joule

E5F08 (B)What is a magnetic field?

B. The space through which a magnetic force acts

E5F09 (D)In what direction is the magnetic field oriented about a conductor in relation to the direction of electron flow?

D. In a direction determined by the left-hand rule

E5F10 (D)What determines the strength of a magnetic field around a conductor?

D. The amount of current

E5F11 (B)What is the term for energy that is stored in an electromagnetic or electrostatic field?

B. Potential energy

E5G01 (A)What is the Q of a parallel R-L-C circuit if the resonant frequency is 14.128 MHz, L is 2.7 microhenrys and R is 18 kilohms?

A. 75.1

E5G02 (C) What is the Q of a parallel R-L-C circuit if the resonant frequency is 4.468 MHz, L is 47 microhenrys and R is 180 ohms?

C. 0.136

E5G03 (D)What is the Q of a parallel R-L-C circuit if the resonant frequency is 7.125 MHz, L is 8.2 microhenrys and R is 1 kilohm?

D. 2.72

E5G04 (B)What is the Q of a parallel R-L-C circuit if the resonant frequency is 7.125 MHz, L is 12.6 microhenrys and R is 22 kilohms?

B. 39

E5G05 (D)What is the Q of a parallel R-L-C circuit if the resonant frequency is 3.625 MHz, L is 42 microhenrys and R is 220 ohms?

D. 0.23

E5G06 (C) Why is a resistor often included in a parallel resonant circuit?

C. To decrease the Q and increase the bandwidth

E5G07 (D)What is the term for an out-of-phase, nonproductive power associated with inductors and capacitors?

D. Reactive power

E5G08 (B)In a circuit that has both inductors and capacitors, what happens to reactive power?

B. It goes back and forth between magnetic and electric fields, but is not dissipated

E5G09 (A)In a circuit where the AC voltage and current are out of phase, how can the true power be determined?

A. By multiplying the apparent power times the power factor

E5G10 (C) What is the power factor of an R-L circuit having a 60 degree phase angle between the voltage and the current?

C. 0.5

E5G11 (B)How many watts are consumed in a circuit having a power factor of 0.2 if the input is 100-V AC at 4 amperes?

B. 80 watts

E5G12 (A)Why would the power used in a circuit be less than the product of the magnitudes of the AC voltage and current?

A. Because there is a phase angle greater than zero between the current and voltage

E5G13 (B)What is the Q of a parallel RLC circuit if the resonant frequency is 14.128 MHz, L is 4.7 microhenrys and R is 18 kilohms?

B. 43.1

E5G14 (D)What is the Q of a parallel RLC circuit if the resonant frequency is 14.225 MHz, L is 3.5 microhenrys and R is 10 kilohms?

D. 31.9

E5G15 (A)What is the Q of a parallel RLC circuit if the resonant frequency is 7.125 MHz, L is 10.1 microhenrys and R is 100 ohms?

A. 0.221

E5G16 (B)What is the Q of a parallel RLC circuit if the resonant frequency is 3.625 MHz, L is 3 microhenrys and R is 2.2 kilohms?

B. 32.2

E5H01 (B)What is the effective radiated power of a repeater station with 50 watts transmitter power output, 4-dB feed line loss, 2-dB duplexer loss, 1-dB circulator loss and 6-dBd antenna gain?

B. 39.7 watts

E5H02 (C) What is the effective radiated power of a repeater station with 50 watts transmitter power output, 5-dB feed line loss, 3-dB duplexer loss, 1-dB circulator loss and 7-dBd antenna gain?

C. 31.5 watts

E5H03 (D)What is the effective radiated power of a station with 75 watts transmitter power output, 4-dB feed line loss and 10-dBd antenna gain?

D. 299 watts

E5H04 (A)What is the effective radiated power of a repeater station with 75 watts transmitter power output, 5-dB feed line loss, 3-dB duplexer loss, 1-dB circulator loss and 6-dBd antenna gain?

A. 37.6 watts

E5H05 (D)What is the effective radiated power of a station with 100 watts transmitter power output, 1-dB feed line loss and 6-dBd antenna gain?

D. 316 watts

E5H06 (B)What is the effective radiated power of a repeater station with 100 watts transmitter power output, 5-dB feed line loss, 3-dB duplexer loss, 1-dB circulator loss and 10-dBd antenna gain?

B. 126 watts

E5H07 (C) What is the effective radiated power of a repeater station with 120 watts transmitter power output, 5-dB feed line loss, 3-dB duplexer loss, 1-dB circulator loss and 6-dBd antenna gain?

C. 60 watts

E5H08 (D)What is the effective radiated power of a repeater station with 150 watts transmitter power output, 2-dB feed line loss, 2.2-dB duplexer loss and 7-dBd antenna gain?

D. 286 watts

E5H09 (A)What is the effective radiated power of a repeater station with 200 watts transmitter power output, 4-dB feed line loss, 3.2-dB duplexer loss, 0.8-dB circulator loss and 10-dBd antenna gain?

A. 317 watts

E5H10 (B)What is the effective radiated power of a repeater station with 200 watts transmitter power output, 2-dB feed line loss, 2.8-dB duplexer loss, 1.2-dB circulator loss and 7-dBd antenna gain?

B. 252 watts

E5H11 (C) What term describes station output (including the transmitter, antenna and everything in between), when considering transmitter power and system gains and losses?

C. Effective radiated power

E5H12 (A)What is reactive power?

A. Wattless, nonproductive power

E5H13 (D)What is the power factor of an RL circuit having a 45 degree phase angle between the voltage and the current?

D. 0.707

E5H14 (C) What is the power factor of an RL circuit having a 30 degree phase angle between the voltage and the current?

C. 0.866

E5H15 (D)How many watts are consumed in a circuit having a power factor of 0.6 if the input is 200V AC at 5 amperes?

D. 600 watts

E5H16 (B)How many watts are consumed in a circuit having a power factor of 0.71 if the apparent power is 500 watts?

B. 355 W

E5I01 (B)What is photoconductivity?

B. The increased conductivity of an illuminated semiconductor junction

E5I02 (A)What happens to the conductivity of a photoconductive material when light shines on it?

A. It increases

E5I03 (D)What happens to the resistance of a photoconductive material when light shines on it?

D. It decreases

E5I04 (C) What happens to the conductivity of a semiconductor junction when light shines on it?

C. It increases

E5I05 (D)What is an optocoupler?

D. An LED and a phototransistor

E5I06 (A)What is an optoisolator?

A. An LED and a phototransistor

E5I07 (B)What is an optical shaft encoder?

B. An array of optocouplers whose light transmission path is controlled by a rotating wheel

E5I08 (D)What characteristic of a crystalline solid will photoconductivity change?

D. The resistance

E5I09 (C) Which material will exhibit the greatest photoconductive effect when visible light shines on it?

C. Cadmium sulfide

E5I10 (B)Which material will exhibit the greatest photoconductive effect when infrared light shines on it?

B. Lead sulfide

E5I11 (A)Which material is affected the most by photoconductivity?

A. A crystalline semiconductor

E5I12 (B)What characteristic of optoisolators is often used in power supplies?

B. They have very high impedance between the light source and the phototransistor

E5I13 (C) What characteristic of optoisolators makes them suitable for use with a triac to form the solid-state equivalent of a mechanical relay for a 120 V AC household circuit?

C. Optoisolators provide a very high degree of electrical isolation between a control circuit and a power circuit