Advanced Amateur Radio - Advanced Theory Practice Exam

Step up to the challenge with hamshack.ca's Advanced Theory Practice Exam, designed to evaluate your expertise in critical theoretical aspects of amateur radio. This exam is an integral component of the Advanced Amateur Radio course suite, specifically structured for those preparing for the Advanced License qualification in Canada. It focuses on five key areas:

Time Constant â€“ Capacitive and Inductive: Testing your understanding of the rate at which capacitors and inductors charge and discharge in a circuit.

Electrostatic and Electromagnetic Fields, Skin Effect: Assessing your knowledge of field theory and the behavior of high-frequency currents on conductor surfaces.

Series-Resonance: Examining your grasp of resonance in circuits where inductance and capacitance are aligned in a series configuration.

Parallel Resonance: Quizzing your understanding of resonance in circuits with parallel-aligned inductance and capacitance.

Quality Factor (Q): Checking your insight into the 'Q' factor, a dimensionless parameter that describes the damping of resonator modes.

This Advanced Theory Practice Exam pulls 25 questions from the question pool, ensuring a comprehensive test of your knowledge in these fundamental areas. The exam setup supports multiple attempts, offering a thorough learning experience and preparation for the actual certification exam.

A-001-003-008: 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

B. 35.4 MHz

C. 35.4 kHz

D. 23.7 kHz

For the given L and C values, the resonant frequency of this series RLC circuit is found to be 23.7 MHz. This frequency denotes the point of resonance in the circuit, where the inductive and capacitive reactances balance each other out, resulting in efficient energy oscillation.

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Category:Series-resonance

A-001-003-009: What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 4 microhenrys and C is 8 picofarads?

A. 28.1 kHz

B. 28.1 MHz

C. 49.7 MHz

D. 49.7 kHz

The resonant frequency for this set of L and C values in a series RLC circuit is calculated to be 28.1 MHz. This is the frequency at which resonance occurs, characterized by the equalization of inductive and capacitive reactances and efficient energy exchange between the inductor and capacitor.

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Category:Series-resonance

A-001-003-005: What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 3 microhenrys and C is 40 picofarads?

A. 13.1 MHz

B. 13.1 kHz

C. 14.5 kHz

D. 14.5 MHz

Using the formula for finding the resonant frequency of a series RLC circuit, the calculated frequency for these L and C values is 14.5 MHz. This is where the circuit resonates, allowing energy to be transferred most efficiently between the inductor and capacitor.

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Category:Parallel resonance

A-001-004-004: What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 2 microhenrys and C is 30 picofarads?

A. 2.65 MHz

B. 2.65 kHz

C. 20.5 kHz

D. 20.5 MHz

This question follows the same principles as the previous ones. When dealing with RLC circuits, understanding the relationship between inductance, capacitance, and resonant frequency is crucial, especially for ham radio operators involved in circuit design and troubleshooting.

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Category:Series-resonance

A-001-003-002: What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 40 microhenrys and C is 200 picofarads?

A. 1.78 kHz

B. 1.78 MHz

C. 1.99 kHz

D. 1.99 MHz

By calculating the resonant frequency using the formula for series RLC circuits, the frequency is found to be 1.78 MHz. This frequency is where the inductive and capacitive reactances in the circuit are equal, allowing for maximum energy transfer between the inductor and capacitor

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Category:Quality factor (Q)

A-001-005-004: What is the Q of a parallel RLC circuit, if it is resonant at 14.225 MHz, L is 3.5 microhenrys and R is 10 kilohms?

A. 31.9

B. 7.35

C. 0.0319

D. 71.5

A Q factor of 31.9 indicates a moderately high selectivity. For ham radio, understanding how to manipulate the Q factor can aid in designing circuits that are more effective at isolating desired signals.

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Category:Time Constant â€“ Capacitance and Inductance

A-001-001-003: 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. A. one exponential rate

B. B. one time constant

C. C. an exponential period of one

D. D. a time factor of one

The term for this duration is one time constant, signifying the time it takes for the current to reach 63.2% of its maximum in an RL circuit.

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Category:Electrostatic and electromagnetic fields, skin effect

A-001-002-009 What is the term for energy that is stored in an electromagnetic or electrostatic field?

A. Potential energy

B. Kinetic energy

C. Ampere-joules

D. Joule-coulombs

Energy stored in an electromagnetic or electrostatic field is referred to as potential energy. This form of energy has the potential to do work and is fundamental in various electrical and electronic components, such as capacitors and inductors, in ham radio circuits.

9 / 25

Category:Parallel resonance

A-001-004-006: What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 3 microhenrys and C is 40 picofarads?

A. 14.5 MHz

B. 1.33 kHz

C. 1.33 MHz

D. 14.5 kHz

Here, the resonant frequency is higher due to a lower inductance and higher capacitance compared to the previous question. Understanding these variations helps in fine-tuning or troubleshooting radio frequency circuits.

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Category:Series-resonance

A-001-003-003: What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 50 microhenrys and C is 10 picofarads?

A. 3.18 kHz

B. 7.12 MHz

C. 7.12 kHz

D. 3.18 MHz

The resonant frequency for these values of L and C in a series RLC circuit is calculated as 7.12 MHz. At this frequency, the circuit exhibits resonance, characterized by equal inductive and capacitive reactances, allowing for efficient energy oscillation between the inductor and capacitor

11 / 25

Category:Electrostatic and electromagnetic fields, skin effect

A-001-002-011 Energy is stored within an inductor that is carrying a current. The amount of energy depends on this current but also depends on a property of the inductor. This property has the following unit:

A. coulomb

B. farad

C. watt

D. henry

The henry is the unit of inductance, which is a key property of an inductor. The amount of energy stored in an inductor is dependent on the current passing through it and its inductance. Inductance measures the ability of the inductor to store energy in its magnetic field.

12 / 25

Category:Electrostatic and electromagnetic fields, skin effect

A-001-002-007Â A wire has a current passing through it. Surrounding the wire there is:

A. a skin effect that diminishes with distance

B. an electromagnetic field

C. an electrostatic field

D. a cloud of electrons

When a current passes through a wire, it generates an electromagnetic field around the wire. This field consists of both electric and magnetic components, which are interrelated and propagate through space as electromagnetic waves.

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Category:Electrostatic and electromagnetic fields, skin effect

A-001-002-004 Why does most of an RF current flow within a very thin layer under the conductorâ€™s surface?

A. a) Because the RF resistance of a conductor is much less than the DC resistance

B. Because a conductor has AC resistance due to self-inductance

C. Because of heating of the conductorâ€™s interior

D. Because of skin effect

The skin effect is the reason why RF current flows primarily in a thin layer just beneath the surface of the conductor. This effect occurs due to the induced eddy currents at high frequencies, which resist the flow of the main current and confine it to the outer layer of the conductor.

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Category:Parallel resonance

A-001-004-011: What is the value of inductance (L) in a parallel RLC circuit, if the resonant frequency is 14.25 MHz and C is 44 picofarads?

A. 0.353 microhenry

B. 2.8 microhenrys

C. 253.8 millihenrys

D. 3.9 millihenrys

This question reverses the usual calculation, asking for inductance given a resonant frequency and capacitance. Such calculations are useful for diagnosing or modifying existing circuits, a common task for advanced amateur radio operators.

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Category:Parallel resonance

A-001-004-003: What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 5 microhenrys and C is 9 picofarads?

A. 3.54 MHz

B. 3.54 kHz

C. 23.7 MHz

D. 23.7 kHz

Again, the resonant frequency is determined by the L and C values. The formula shows that frequency is inversely proportional to the square root of the product of L and C, meaning that changes in these components will inversely affect the resonant frequency.

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Category:Time Constant â€“ Capacitance and Inductance

A-001-001-010: What is time constant of a circuit having a 220 microfarad capacitor in series with a 470 kilohm resistor?

A. 470 seconds

B. 220 seconds

C. 103 seconds

D. 470 000 seconds

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Category:Quality factor (Q)

A-001-005-001: What is the Q of a parallel RLC circuit, if it is resonant at 14.128 MHz, L is 2.7 microhenrys and R is 18 kilohms?

A. 7.51

B. 0.013

C. 71.5

D. 75.1

The Q factor, or Quality factor, represents the efficiency of the RLC circuit at its resonant frequency. A higher Q value indicates a sharper resonance peak, meaning the circuit is more selective about its resonant frequency. It's important for ham radio operators to understand Q factor for effective signal filtering and tuning.

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Category:Quality factor (Q)

A-001-005-003: What is the Q of a parallel RLC circuit, if it is resonant at 4.468 MHz, L is 47 microhenrys and R is 180 ohms?

A. 0.00735

B. 13.3

C. 0.136

D. 7.35

In this case, the low Q factor indicates a broader resonance peak, meaning the circuit is less selective about its resonant frequency. This could be beneficial in applications where a wider range of frequencies needs to be accommodated.

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Category:Time Constant â€“ Capacitance and Inductance

A-001-001-005:Â What is meant by "back EMF"?

A. a current that opposes the applied EMF

B. an opposing EMF equal to R times C percent of the applied EMF

C. a current equal to the applied EMF

D. a voltage that opposes the applied EMF

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Category:Electrostatic and electromagnetic fields, skin effect

A-001-002-001 What is the result of skin effect?

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

B. Thermal effects on the surface of the conductor increase impedance.

C. Thermal effects on the surface of the conductor decrease impedance.

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

The skin effect causes the RF current to flow in a thinner layer on the surface of the conductor at higher frequencies. This occurs due to the inductive properties of the conductor, which increase with frequency, leading to a decrease in the depth (skin depth) at which the current can penetrate the conductor.

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Category:Quality factor (Q)

A-001-005-005: What is the Q of a parallel RLC circuit, if it is resonant at 7.125 MHz, L is 8.2 microhenrys and R is 1 kilohm?

A. 0.368

B. 0.273

C. 2.73

D. 36.8

This Q factor indicates a relatively broad resonance, which can be useful in applications where filtering a range of frequencies is needed rather than focusing on a very narrow band.

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Category:Quality factor (Q)

A-001-005-009: What is the Q of a parallel RLC circuit, if it is resonant at 3.625 MHz, L is 42 microhenrys and R is 220 ohms?

A. 0.00435

B. 0.23

C. 2.3

D. 4.35

The low Q value here indicates a wider resonance. This can be useful in applications where a broader range of frequencies is acceptable, or where highly selective filtering is not necessary.

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Category:Series-resonance

A-001-003-007: What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 8 microhenrys and C is 7 picofarads?

A. 28.4 MHz

B. 2.84 MHz

C. 21.3 MHz

D. 2.13 MHz

The calculated resonant frequency for these L and C values in a series RLC circuit is 21.3 MHz. At this frequency, the circuit resonates, enabling maximal energy transfer between the inductor and capacitor with the impedance being purely resistive.

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Category:Time Constant â€“ Capacitance and Inductance

A-001-001-008: What is the time constant of a circuit having a 100 microfarad capacitor in series with a 470 kilohm resistor?

A. 47 seconds

B. 4700 seconds

C. 470 seconds

D. 0.47 seconds

The time constant of an RC circuit is calculated by multiplying the resistance (in ohms) by the capacitance (in farads). For a 470 kilohm resistor and a 100 microfarad capacitor, the time constant is 47 seconds.

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Category:Time Constant â€“ Capacitance and Inductance

A-001-001-004: 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?

A. One time constant

B. A discharge factor of one

C. An exponential discharge of one

D. One discharge period

The time constant in an RC circuit is the time required for the voltage across the capacitor to discharge to about 36.8% of its initial value, as it represents the time to reach 63.2% of the final value during charging or discharging.

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