A series RLC circuit has L = 50 microhenries and C = 200 picofarads. What is its approximate resonant frequency?
Electrical Principles And Components
Question · Medium
The inductive reactance of a coil at a given frequency is 314 ohms. If the frequency is doubled, what is the new inductive reactance?
Question · Easy
Chapter 1: DC Theory, Circuit Laws & Passive Components
1.1 DC Circuit Analysis, Ohm's Law, and Kirchhoff's Laws
Study guide
A parallel resonant (tank) circuit has a resonant frequency of 7.1 MHz and a bandwidth of 71 kHz between the half-power points. What is its quality factor Q?
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In a circuit containing both resistance and reactance, the impedance is found from which relationship?
Two 100-ohm resistors are connected in parallel, and that combination is placed in series with a 25-ohm resistor. What is the total resistance?
A low-pass filter is most commonly fitted at the output of an HF transmitter primarily to:
1.2 AC Fundamentals, Sine Waves, Peak, RMS, and Phase Relationships
The capacitive reactance of a 100-picofarad capacitor at 14 MHz is approximately:
In a linear regulated DC power supply, the role of the series pass transistor is to:
A full-wave bridge rectifier driven from a 50 Hz mains supply produces an output ripple frequency of:
Which property best describes the behaviour of a Zener diode used in a voltage reference circuit?
1.3 Inductance, Capacitance, Reactance, and Time Constants
In a bipolar junction transistor amplifier, the term 'beta' (hfe) refers to:
A thermionic valve (vacuum tube) used as an RF power amplifier requires which electrode to be heated to release electrons?
The phase relationship between voltage and current in a purely capacitive AC circuit is:
A power amplifier draws 20 A from a 13.8 V supply and delivers 120 W of RF output. What is its DC-to-RF efficiency?
Question · Hard
Chapter 2: Impedance, Resonance & Passive Filters
2.1 Complex Impedance, Phasors, and AC Circuit Analysis
What does the time constant of an RC circuit represent?
A toroidal inductor is often preferred over a solenoid wound on an air-cored former because the toroid:
The effective (RMS) value of a sine wave that has a peak value of 100 V is approximately:
In a high-Q parallel LC tank circuit at resonance, the impedance presented to the source is:
2.2 Series and Parallel LC Resonance and Q Factor
A field-effect transistor (FET) differs from a bipolar transistor mainly in that the FET is:
If three 1500-ohm resistors are connected in parallel, the total resistance is:
A Colpitts oscillator is identified by its use of which components to determine the feedback ratio and frequency?
Radio Circuits And Systems
In a superheterodyne receiver, the intermediate frequency (IF) is produced by:
2.3 Passive Filters, Cutoff Frequency, and Attenuator Pads
A class C amplifier is generally unsuitable for amplifying a single-sideband (SSB) signal because it:
In an SSB transmitter, the unwanted sideband is most commonly removed using:
Frequency modulation (FM) differs from amplitude modulation (AM) in that, for FM, the modulating signal varies the carrier's:
A phase-locked loop (PLL) frequency synthesiser holds its output on frequency by comparing the divided VCO output against a:
Chapter 3: Semiconductor Devices & Power Supplies
3.1 Semiconductor Diodes, Zener Regulators, and Rectifier Circuits
In a software-defined radio (SDR) using direct sampling, the analogue-to-digital converter sampling rate must be at least:
Image rejection in a single-conversion superheterodyne receiver is improved by:
A class A amplifier conducts for what portion of the input cycle?
Why is a crystal oscillator more frequency-stable than a typical LC oscillator?
3.2 Bipolar Junction Transistors, FETs, and Operational Amplifiers
A balanced mixer is desirable in a transmitter or receiver because it:
For an AM signal with a carrier and two sidebands, what fraction of the total transmitted power is in the carrier at 100 percent modulation?
An automatic gain control (AGC) circuit in a receiver functions to:
Compared with narrowband FM, wideband FM provides:
3.3 Thermionic Valves (Vacuum Tubes) and High-Power Linear Amplifiers
A 50-ohm transmission line is terminated in a 150-ohm resistive load. What is the resulting voltage standing wave ratio (VSWR)?
Transmission Lines And Antennas
The velocity factor of a coaxial cable is 0.66. What physical length of cable is needed to make an electrical quarter-wavelength at 7.0 MHz?
A half-wave dipole in free space has a nominal feedpoint impedance of approximately:
Adding directors and a reflector to a driven dipole to form a Yagi antenna primarily:
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