Electrical Math

Key Topic 9:  Ohm’s Law-1

3-9B1 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?

A. 4 megohms.

B. 2 megohms.

C. 400 kilohms.

D. 200 kilohms.

Electrical Math

Key Topic 9:  Ohm’s Law-1

3-9B2 Which of the following Ohms Law formulas is incorrect?

A. I = E / R

B. I = R / E

C. E = I x R

D. R = E / I

Electrical Math

Key Topic 9:  Ohm’s Law-1

3-9B3 If a current of 2 amperes flows through a 50-ohm resistor, what is the voltage across the resistor?

A. 25 volts.

B. 52 volts.

C. 200 volts.

D. 100 volts.

Electrical Math

Key Topic 9:  Ohm’s Law-1

3-9B4 If a 100-ohm resistor is connected across 200 volts, what is the current through the resistor?

A. 2 amperes.

B. 1 ampere.

C. 300 amperes.

D. 20,000 amperes.

Electrical Math

Key Topic 9:  Ohm’s Law-1

3-9B5 If a current of 3 amperes flows through a resistor connected to 90 volts, what is the resistance?

A. 3 ohms.

B. 30 ohms.

C. 93 ohms.

D. 270 ohms.

Electrical Math

Key Topic 9:  Ohm’s Law-1

3-9B6 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?

A. 150 ohms.

B. 220 ohms.

C. 380 ohms.

D. 470 ohms.

Electrical Math

Key Topic 10:  Ohm’s Law-2

3-10B1 What is the peak-to-peak RF voltage on the 50 ohm output of a 100 watt transmitter?

A. 70 volts.

C. 140 volts.

B. 100 volts.

D. 200 volts.

Electrical Math

Key Topic 10:  Ohm’s Law-2

3-10B2 What is the maximum DC or RMS voltage that may be connected across a 20 watt, 2000 ohm resistor?

A. 10 volts.

B. 100 volts.

C. 200 volts. 

D. 10,000 volts.

Electrical Math

Key Topic 10:  Ohm’s Law-2

3-10B3 A 500-ohm, 2-watt resistor and a 1500-ohm, 1-watt resistor are connected in parallel. What is the maximum voltage that can be applied across the parallel circuit without exceeding wattage ratings?

A. 22.4 volts.

B. 31.6 volts.

C. 38.7 volts. 

D. 875 volts.

Electrical Math

Key Topic 10:  Ohm’s Law-2

3-10B4 In Figure 3B1, what is the voltage drop across R1?

[image] 

A. 9 volts.

B. 7 volts.

C. 5 volts. 

D. 3 volts.

Electrical Math

Key Topic 10:  Ohm’s Law-2

3-10B5 In Figure 3B2, what is the voltage drop across R1?

[image]

A. 1.2 volts.

B. 2.4 volts.

C. 3.7 volts. 

D. 9 volts.

Electrical Math

Key Topic 10:  Ohm’s Law-2

3-10B6 What is the maximum rated current-carrying capacity of a resistor marked “2000 ohms, 200 watts”?

A. 0.316 amps.

B. 3.16 amps.

C. 10 amps.

D. 100 amps.

Electrical Math

Key Topic 11:  Frequency

3-11B1 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?

A. 46.21 Hz.

B. 0.1 MHz.

C. 462.1 Hz.

D. 0.2 MHz.

Electrical Math

Key Topic 11:  Frequency

3-11B2 The second harmonic of a 380 kHz frequency is:

A. 2 MHz.

B. 760 kHz.

C. 190 kHz.

D. 144.4 GHz.

Electrical Math

Key Topic 11:  Frequency

3-11B3 What is the second harmonic of SSB frequency 4146 kHz?

A. 8292 kHz.

B. 4.146 MHz.

C. 2073 kHz.

D. 12438 kHz.

Electrical Math

Key Topic 11:  Frequency

3-11B4 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?

A. 165.2 Hz.

B. 15.652 kHz.

C. 156.52 Hz.

D. 1.4652 MHz.

Electrical Math

Key Topic 11:  Frequency

3-11B5 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?

A. 146.52 Hz.

B. 1565.20 Hz.

C. 10 Hz.

D. 156.52 kHz.

Electrical Math

Key Topic 11:  Frequency

3-11B6 What is the most the actual transmitter frequency could differ from a reading of 462,100,000 hertz on a frequency counter with a time base accuracy of ± 1.0 ppm?

A. 46.21 MHz.

B. 10 Hz.

C. 1.0 MHz.

D. 462.1 Hz.

Electrical Math

Key Topic 12:  Waveforms

3-12B1 At pi/3 radians, what is the amplitude of a sine-wave having a peak value of 5 volts?

A. -4.3 volts.

B. -2.5 volts.

C. +2.5 volts. 

D. +4.3 volts.

Electrical Math

Key Topic 12:  Waveforms

3-12B2 At 150 degrees, what is the amplitude of a sine-wave having a peak value of 5 volts?

A. -4.3 volts.

B. -2.5 volts.

C. +2.5 volts.

D. +4.3 volts.

Electrical Math

Key Topic 12:  Waveforms

3-12B3 At 240 degrees, what is the amplitude of a sine-wave having a peak value of 5 volts?

A. -4.3 volts.

B. -2.5 volts.

C. +2.5 volts.

D. +4.3 volts.

Electrical Math

Key Topic 12:  Waveforms

3-12B4 What is the equivalent to the root-mean-square value of an AC voltage?

A. 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.

C. The AC voltage found by taking the square of the average value of the peak AC voltage.

D. The DC voltage causing the same heating in a given resistor as the RMS AC voltage of the same value.

Electrical Math

Key Topic 12:  Waveforms

3-12B5 What is the RMS value of a 340-volt peak-to-peak pure sine wave?

A. 170 volts AC.

B. 240 volts AC.

C. 120 volts AC. 

D. 350 volts AC.

Electrical Math

Key Topic 12:  Waveforms

3-12B6 Determine the phase relationship between the two signals shown in Figure 3B3.

[image]

A. A is lagging B by 90 degrees.

B. B is lagging A by 90 degrees.

C. A is leading B by 180 degrees.

D. B is leading A by 90 degrees.

Electrical Math

Key Topic 13:  Power Relationships

3-13B1 What does the power factor equal in an R-L circuit having a 60 degree phase angle between the voltage and the current?

A. 0.414

B. 0.866

C. 0.5

D. 1.73

Electrical Math

Key Topic 13:  Power Relationships

3-13B2 If a resistance to which a constant voltage is applied is halved, what power dissipation will result?

A. Double.

B. Halved.

C. Quadruple.

D. Remain the same.

Electrical Math

Key Topic 13:  Power Relationships

3-13B3 746 watts, corresponding to the lifting of 550 pounds at the rate of one-foot-per-second, is the equivalent of how much horsepower?

A. One-quarter horsepower.

B. One-half horsepower.

C. Three-quarters horsepower.

D. One horsepower.

Electrical Math

Key Topic 13:  Power Relationships

3-13B4 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.

B. By subtracting the apparent power from the power factor.

C. By dividing the apparent power by the power factor.

D. By multiplying the RMS voltage times the RMS current.

Electrical Math

Key Topic 13:  Power Relationships

3-13B5 What does the power factor equal in an R-L circuit having a 45 degree phase angle between the voltage and the current?

A. 0.866

B. 1.0

C. 0.5

D. 0.707

Electrical Math

Key Topic 13:  Power Relationships

3-13B6 What does the power factor equal in an R-L circuit having a 30 degree phase angle between the voltage and the current?

A. 1.73

B. 0.866

C. 0.5

D. 0.577

Electrical Math

Key Topic 14:  RC Time Constants-1

3-14B1 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?

A. An exponential rate of one.

B. One time constant.

C. One exponential period.

D. A time factor of one.

Electrical Math

Key Topic 14:  RC Time Constants-1

3-14B2 What is the meaning of the term “time constant of an RC circuit”? The time required to charge the capacitor in the circuit to:

A. 23.7% of the supply voltage.

B. 36.8% of the supply voltage.

C. 57.3% of the supply voltage.

D. 63.2% of the supply voltage.

Electrical Math

Key Topic 14:  RC Time Constants-1

3-14B3 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.

B. An exponential period of one.

C. A time factor of one.

D. One exponential rate.

Electrical Math

Key Topic 14:  RC Time Constants-1

3-14B4 What is the meaning of the term “time constant of an RL circuit”? The time required for the:

A. Current in the circuit to build up to 36.8% of the maximum value.

B. Voltage in the circuit to build up to 63.2% of the maximum value.

C. Current in the circuit to build up to 63.2% of the maximum value.

D. Voltage in the circuit to build up to 36.8% of the maximum value.

Electrical Math

Key Topic 14:  RC Time Constants-1

3-14B5 After two time constants, the capacitor in an RC circuit is charged to what percentage of the supply voltage?

A. 36.8 %

B. 63.2 %

C. 86.5 %

D. 95 %

Electrical Math

Key Topic 14:  RC Time Constants-1

3-14B6 After two time constants, the capacitor in an RC circuit is discharged to what percentage of the starting voltage?

A. 86.5 %

B. 13.5 %

C. 63.2 %

D. 36.8 %

Electrical Math

Key Topic 15:  RC Time Constants-2

3-15B1 What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors all in parallel?

A. 22 seconds.

B. 44 seconds.

C. 440 seconds.

D. 220 seconds.

Electrical Math

Key Topic 15:  RC Time Constants-2

3-15B2 What is the time constant of a circuit having two 100-microfarad capacitors and two 470-kilohm resistors all in series?

A. 470 seconds.

B. 47 seconds.

C. 4.7 seconds.

D. 0.47 seconds.

Electrical Math

Key Topic 15:  RC Time Constants-2

3-15B3 What is the time constant of a circuit having a 100-microfarad capacitor and a 470-kilohm resistor in series?

A. 4700 seconds.

B. 470 seconds.

C. 47 seconds.

D. 0.47 seconds.

Electrical Math

Key Topic 15:  RC Time Constants-2

3-15B4 What is the time constant of a circuit having a 220-microfarad capacitor and a 1-megohm resistor in parallel?

A. 220 seconds.

B. 22 seconds.

C. 2.2 seconds.

D. 0.22 seconds.

Electrical Math

Key Topic 15:  RC Time Constants-2

3-15B5 What is the time constant of a circuit having two 100-microfarad capacitors and two 470-kilohm resistors all in parallel?

A. 470 seconds.

B. 47 seconds.

C. 4.7 seconds.

D. 0.47 seconds.

Electrical Math

Key Topic 15:  RC Time Constants-2

3-15B6 What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors all in series?

A. 220 seconds.

B. 55 seconds.

C. 110 seconds.

D. 440 seconds.

Electrical Math

Key Topic 16:  Impedance Networks-1

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.

A. 20 -j19

B. 19 +j20

C. 20 +j19

D. 19 -j20

Electrical Math

Key Topic 16:  Impedance Networks-1

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?

A. 30 -j3

B. 3 +j30

C. 3 -j30

D. 30 +j3

Electrical Math

Key Topic 16:  Impedance Networks-1

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

B. 40 -j31400

C. 31400 +j40

D. 31400 -j40

Electrical Math

Key Topic 16:  Impedance Networks-1

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?

A. 200 - j188

B. 200 + j188

C. 188 + j200

D. 188 - j200

Electrical Math

Key Topic 16:  Impedance Networks-1

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?

A. 150 - j159

B. 150 + j159

C. 159 - j150

D. 159 + j150

Electrical Math

Key Topic 16:  Impedance Networks-1

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?

A. 318 - j400

B. 400 + j318

C. 318 + j400

D. 400 - j318

Electrical Math

Key Topic 17:  Impedance Networks-2

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.

A. 2490 ohms, /51.5 degrees

B. 4000 ohms, /38.5 degrees

C. 5112 ohms, /-38.5 degrees

D. 2490 ohms, /-51.5 degrees

Electrical Math

Key Topic 17:  Impedance Networks-2

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?

A. 121 ohms, /35 degrees

B. 141 ohms, /45 degrees

C. 161 ohms, /55 degrees

D. 181 ohms, /65 degrees

Electrical Math

Key Topic 17:  Impedance Networks-2

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?

A. 240 ohms, /36.9 degrees

B. 240 ohms, /-36.9 degrees

C. 500 ohms, /-53.1 degrees

D. 500 ohms, /53.1 degrees

Electrical Math

Key Topic 17:  Impedance Networks-2

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

B. 400 ohms, /27 degrees

C. 300 ohms, /17 degrees

D. 200 ohms, /10 degrees

Electrical Math

Key Topic 17:  Impedance Networks-2

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?

A. 240 ohms, /-36.9 degrees

B. 240 ohms, /36.9 degrees

C. 500 ohms, /53.1 degrees

D. 500 ohms, /-53.1 degrees

Electrical Math

Key Topic 17:  Impedance Networks-2

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

A. To show the reactance which is present.

B. To graphically represent the AC and DC component.

C. To display the data on an XY chart.

D. The plot shows the magnitude and phase angle.

Electrical Math

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?

A. 6.6 ohms.

B. 11 ohms.

C. 18 ohms.

D. 23 ohms.

Electrical Math

Key Topic 18:  Calculations

3-18B2 A 1-watt, 10-volt Zener diode with the following characteristics: Imin. = 5 mA; Imax. = 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?

A. 100 ohms.

B. 200 ohms.

C. 1 kilohms.

D. 2 kilohms.

Electrical Math

Key Topic 18:  Calculations

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?

A. 17 %

B. 80 %

C. 20 %

D. 83 %

Electrical Math

Key Topic 18:  Calculations

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.

B. 14.2 to 1.

C. 50 to 1.

D. None of these.

Electrical Math

Key Topic 18:  Calculations

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?

A. 150 volts.

B. 160 volts.

C. 240 volts.

D. 250 volts.

Electrical Math

Key Topic 18:  Calculations

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

A. 0.25 Siemens (mhos).

B. 0.50 Siemens (mhos).

C. 1.00 Siemens (mhos).

D. 1.25 Siemens (mhos).