B-005 — Basic electronics and theory

The theory: Ohm's law, power, series and parallel circuits, AC and DC, frequency and wavelength, decibels, and the metric prefixes the exam leans on.

All 142 questions

• B-005-001-001 If a dial marked in megahertz shows a reading of 3.525 MHz, what would it show if it were marked in kilohertz?
• B-005-001-002 If an ammeter marked in amperes is used to measure a 3000-milliampere current, what reading would it show?
• B-005-001-003 How many hertz is 1 kHz?
• B-005-001-004 How many microfarads is 1 000 000 picofarads?
• B-005-001-005 If you have a hand-held transceiver that puts out 500 milliwatts, how many watts would this be?
• B-005-001-006 A kilohm is:
• B-005-001-007 How many megahertz is 7040 kHz?
• B-005-001-008 A current of one quarter ampere may be written as:
• B-005-001-009 How many millivolts equal two volts?
• B-005-001-010 How can a frequency in megahertz be stated in gigahertz?
• B-005-001-011 How many millihenries equal 10 000 microhenries?
• B-005-002-001 Which of these groups lists three good electrical conductors?
• B-005-002-002 Which of these groups lists three good electrical insulators?
• B-005-002-003 What do we call the flow of electric charge in a circuit?
• B-005-002-004 What is the best conductor among the following materials?
• B-005-002-005 Which of these types of materials readily allows the flow of electric current?
• B-005-002-006 What electrical property causes an object to conduct electricity very well?
• B-005-002-007 The letter "R" is the symbol for:
• B-005-002-008 What is the inverse of resistance?
• B-005-002-009 What is a voltage drop?
• B-005-002-010 The resistance of a conductor changes with:
• B-005-002-011 Which term describes the direction of current in a DC circuit?
• B-005-003-001 What term describes the rate at which electrical energy is used?
• B-005-003-002 If you have light bulbs marked 40 watts, 50 watts, 60 watts and 100 watts, which one will consume electrical energy at the highest rate?
• B-005-003-003 What is the basic unit of electrical power?
• B-005-003-004 A circuit consists of a battery and load resistor. What circuit malfunction would cause no current to be drawn from the battery?
• B-005-003-005 Which electrical circuit draws too much current?
• B-005-003-006 Power is expressed in:
• B-005-003-007 Which of the following two quantities should be multiplied together to find power?
• B-005-003-008 Which two electrical units multiplied together give the unit "watts"?
• B-005-003-009 A resistor in a circuit becomes very hot and starts to burn. This is because the resistor is dissipating too much:
• B-005-003-010 When speaking of electrical circuits, what does the term "continuity" mean?
• B-005-003-011 You have acquired a transceiver and connected it to a power supply. When you switch on the power supply, its fuse blows immediately. What circuit malfunction caused the fuse to blow?
• B-005-004-001 What is the voltage across a 2-ohm resistor if a current of 0.5 amperes flows through it?
• B-005-004-002 How is the current in a DC circuit calculated when the voltage and resistance are known?
• B-005-004-003 How is the resistance in a DC circuit calculated when the voltage and current are known?
• B-005-004-004 How is the voltage in a DC circuit calculated when the current and resistance are known?
• B-005-004-005 What is the resistance of a circuit that draws 0.25 amperes from a 12-volt source?
• B-005-004-006 What value of resistance is required to drop 9 volts with a current of 10 milliamperes?
• B-005-004-007 If the current flowing through a 50-ohm resistor is 0.44 amperes, what voltage would you measure across the resistor?
• B-005-004-008 A 30-ohm resistor is connected across a 6-volt battery. What current does it draw?
• B-005-004-009 What voltage is needed to supply a current of 200 milliamperes to operate a relay that has a resistance of 25 ohms?
• B-005-004-010 What formula calculates the resistance of a circuit when the voltage and current are known?
• B-005-004-011 What is the resistance of a circuit if it draws 300 milliamperes from a 3-volt battery?
• B-005-005-001 In a parallel circuit with a voltage source and several branch resistors, how is the total current related to the current in the branch resistors?
• B-005-005-002 You connect four 100-ohm resistors in parallel across a 12-volt battery. How many milliamperes of current are drawn from the battery?
• B-005-005-003 Several resistors of various values are connected in parallel. How does the total resistance of the combination compare to the individual resistors?
• B-005-005-004 Two 1000-ohm resistors are connected in parallel across a 12-volt battery. What is the total current?
• B-005-005-005 The total resistance of resistors connected in series is:
• B-005-005-006 What is the total resistance of five 10-ohm resistors in series?
• B-005-005-007 Which of these series combination of resistors would replace a single 120-ohm resistor?
• B-005-005-008 If ten resistors of equal value "R" are wired in parallel, what formula yields the total resistance?
• B-005-005-009 What is the total resistance of four 68-ohm resistors wired in parallel?
• B-005-005-010 Two resistors are in parallel. Resistor "A" carries twice the current of resistor "B," which means that:
• B-005-005-011 The total current in a parallel circuit is equal to the:
• B-005-006-001 Why would a large size resistor be used instead of a smaller one of the same resistance?
• B-005-006-002 A load requires 12 volts DC at 5 amperes. What is the minimum required power transformer rating?
• B-005-006-003 What is the DC input power of a transmitter operating at 12 volts and drawing 500 milliamperes?
• B-005-006-004 When two 500-ohm 1-watt resistors are connected in series, the maximum total power that can be dissipated by the resistors is:
• B-005-006-005 When two 500-ohm 1-watt resistors are connected in parallel, they can dissipate a maximum total power of:
• B-005-006-006 If the voltage applied to two resistors in series is doubled, how much will the total power change?
• B-005-006-007 Which of these combinations of resistors could make up a 50-ohm dummy load capable of safely dissipating 5 watts?
• B-005-006-008 How much current is drawn by a 12-volt, 30-watt light bulb?
• B-005-006-009 What is the power consumption of two 10-ohm resistors connected in series with a 10-volt battery?
• B-005-006-010 What is the advantage of replacing a 50-ohm resistor with a parallel combination of two 100-ohm resistors of the same power rating?
• B-005-006-011 Resistor wattage ratings are:
• B-005-007-001 What is the term for the number of times per second an alternating current completes a positive to negative cycle?
• B-005-007-002 What approximate range of frequencies can most humans hear?
• B-005-007-003 Why is the range of frequencies from 20 Hz to 20 kHz termed audio frequencies?
• B-005-007-004 Electrical energy at a frequency of 7125 kHz is in what frequency range?
• B-005-007-005 What is the name for the distance an AC signal travels during one complete cycle?
• B-005-007-006 What happens to a signal's wavelength as its frequency increases?
• B-005-007-007 What happens to a signal's frequency as its wavelength gets shorter?
• B-005-007-008 What does 60 hertz (Hz) mean?
• B-005-007-009 Two AC waveforms have the same frequency, but their cycles do not begin at the same instant. What term describes that timing difference?
• B-005-007-010 What is the shape of the waveform of the electricity supplied from a household receptacle?
• B-005-007-011 A signal is composed of a fundamental frequency of 2 kHz and another of 4 kHz. What name is given to the 4 kHz signal?
• B-005-008-001 A two-times increase in power results in a change of how many dB?
• B-005-008-002 What change in transmitter power results in a 3 dB decrease?
• B-005-008-003 What change in transmitter power results in a 6 dB increase?
• B-005-008-004 If a signal transmitted with a power of 200 watts is received with an S-meter reading of "10 dB over S9," what would be the new reading if power was reduced to 20 watts?
• B-005-008-005 If a signal transmitted with a power of 150 watts is received with an S-meter reading of "20 dB over S9," what would be the new reading if power was reduced to 15 watts?
• B-005-008-006 What is the "decibel" used for?
• B-005-008-007 The power output from a transmitter increases from 1 watt to 2 watts. How many decibels does that increase represent?
• B-005-008-008 The power of a transmitter is increased from 5 watts to 50 watts by a linear amplifier. The power gain, expressed in dB, is:
• B-005-008-009 You add a 9 dB gain amplifier to your 2-watt hand-held. What is the power output of the combination?
• B-005-008-010 The power of your transmitter is 100 watts and your transmission line introduces a loss of 6 dB. How much power is delivered to the antenna?
• B-005-008-011 A local amateur radio operator reports receiving your 100-watt 2-metre simplex transmission with an S-meter reading of "30 dB over S9." What power could you use to reduce that reading to S9?
• B-005-009-001 If two equal-value inductors are connected in series, what is their total inductance?
• B-005-009-002 If two equal-value inductors are connected in parallel, what is their total inductance?
• B-005-009-003 If two equal-value capacitors are connected in series, what is their total capacitance?
• B-005-009-004 If two equal-value capacitors are connected in parallel, what is their total capacitance?
• B-005-009-005 You are constructing an air-core inductor using a coil of wire. What parameters determine its inductance?
• B-005-009-006 A capacitor is made of two identical metal plates separated by air. What parameters determine its capacitance?
• B-005-009-007 What precaution must you take when using polarized electrolytic capacitors?
• B-005-009-008 If you wire two 12-millihenry chokes in series, what is the inductance of the combination?
• B-005-009-009 If you wire two 20-millihenry inductors in parallel, what is the inductance of the combination?
• B-005-009-010 If you wire two 20-microfarad capacitors in series, what is the capacity of the combination?
• B-005-009-011 If you wire two 24-microfarad capacitors in parallel, what is the capacity of the combination?
• B-005-010-001 How does an inductor react to AC?
• B-005-010-002 How does a capacitor react to AC?
• B-005-010-003 The reactance of capacitors increases as:
• B-005-010-004 What is the term for the opposition to alternating current caused by the combined effect of reactance and resistance?
• B-005-010-005 What term equals the ratio of AC voltage to AC current in a system or circuit?
• B-005-010-006 What circuit parameter change causes an inductor's reactance to increase?
• B-005-010-007 What property allows a coil wound on a ferrite core to mitigate the effects of an offending radio signal?
• B-005-010-008 What property allows a bypass capacitor in an audio circuit to divert an interfering RF signal?
• B-005-010-009 What property allows an RF bypass capacitor to have little effect on an audio circuit?
• B-005-010-010 What property allows an RF choke coil to have little effect on signals meant to flow through the coil?
• B-005-010-011 In general, the reactance of inductors increases with:
• B-005-011-001 A transformer with a 120-volt primary voltage supplies 250 watts to a transmitter. Neglecting losses, what is the approximate primary current?
• B-005-011-002 How can a transformer with two windings change impedance?
• B-005-011-003 A transformer with a single 12-volt secondary draws 0.5 amperes through its 120-volt primary. Assuming no losses, what current is drawn from the secondary?
• B-005-011-004 The primary winding of a transformer has 250 turns, and the secondary has 500 turns. If the input voltage is 120 volts, what is the secondary voltage?
• B-005-011-005 The strength of the magnetic field around a conductor in air is:
• B-005-011-006 Maximum induced voltage in a coil occurs when:
• B-005-011-007 A transformer primary winding consumes 10 watts. Neglecting losses, if the secondary voltage is 5 volts, what is the secondary current?
• B-005-011-008 A step-up transformer with a primary to secondary turns ratio of 1:5 delivers 50 milliamperes to a load. Assuming 100% efficiency, what is the primary current?
• B-005-011-009 When is coupling (induction) between two wires maximum?
• B-005-011-010 A permanent magnet would most likely be made from:
• B-005-011-011 What confirms the fact that the transfer of energy from the primary to the secondary of a transformer is not perfect?
• B-005-012-001 Resonance is the condition that exists when:
• B-005-012-002 At resonance, what impedance does a parallel tuned circuit exhibit?
• B-005-012-003 While the resonant frequency of a tuned circuit is a single frequency, the effect of resonance is significant over a certain range of frequencies. What is this range called?
• B-005-012-004 What two components are required to form a tuned circuit?
• B-005-012-005 When a parallel coil-capacitor combination is supplied with AC of different frequencies, there will be one frequency where the impedance will be highest. This is the:
• B-005-012-006 In a parallel-resonant circuit at resonance, the circuit has:
• B-005-012-007 In a series resonant circuit at resonance, the circuit has:
• B-005-012-008 A coil and an air-spaced capacitor are arranged to form a resonant circuit. The resonant frequency will remain the same if we:
• B-005-012-009 Resonant circuits in a receiver are used to:
• B-005-012-010 Resonance is the condition that exists when:
• B-005-012-011 What happens to current when a series RLC circuit is tuned to the frequency of the source?
• B-005-013-001 How is a voltmeter usually connected to a circuit under test?
• B-005-013-002 How is an ammeter usually connected to a circuit under test?
• B-005-013-003 What does a multimeter measure?
• B-005-013-004 What is the correct instrument to measure the final power amplifier current?
• B-005-013-005 When measuring the voltage across a circuit component, what does the voltmeter appear to be in the circuit?
• B-005-013-006 When measuring current drawn from a DC power supply, what does the ammeter placed in the circuit appear as?
• B-005-013-007 What instrument can provide a direct measurement of power at the output of a transmitter?
• B-005-013-008 Potential difference is measured by means of:
• B-005-013-009 What instrument is used to measure electrical current?
• B-005-013-010 What term describes the ability of an instrument to display values that are true to reality?