What is the inductive reactance (XL) of a 10 microhenry inductor at a frequency of 7 MHz? (XL = 2*pi*f*L)
Advanced Theory
Question · Medium
As the frequency applied to a capacitor increases, its capacitive reactance (XC):
Question · Easy
In a series circuit containing resistance R and reactance X, the impedance Z is found by:
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In a purely inductive AC circuit, the current:
At the resonant frequency of a series LC circuit, the inductive and capacitive reactances:
The resonant frequency of an LC circuit is given by which formula?
A parallel LC circuit (tank circuit) at resonance presents:
The Q (quality factor) of a resonant circuit is a measure of:
A resonant circuit has a center frequency of 7.0 MHz and a Q of 70. What is its approximate bandwidth? (BW = f/Q)
A filter that passes frequencies below its cutoff and attenuates those above it is called a:
To suppress harmonics at the output of an HF transmitter so they are not radiated, you would typically use a:
In a series RLC circuit at resonance, what is the phase angle between the applied voltage and the current?
Two capacitors of 100 pF and 100 pF are connected in series. The total capacitance is:
What is the capacitive reactance (XC) of a 100 pF capacitor at 1 MHz? (XC = 1/(2*pi*f*C))
Question · Hard
In an AC circuit, true power dissipated as heat in the resistance is called:
The power factor of an AC circuit is the ratio of:
If a series resonant circuit has a higher Q, its selectivity (ability to discriminate between frequencies) is:
Skin effect in a conductor at radio frequencies causes:
An inductor of 5 microhenries and a capacitor of 50 pF form a resonant circuit. Increasing the capacitance to 200 pF will cause the resonant frequency to:
In a parallel circuit with resistance and inductive reactance, total current is found by:
The reactance of an ideal capacitor at DC (0 Hz) is:
A band-pass filter is most useful in a receiver to:
The total impedance of a 30 ohm resistance in series with a 40 ohm reactance is:
A circuit shows current leading voltage by 90 degrees. The circuit is:
Loading (increasing the load current) on a high-Q resonant circuit will generally:
A Class A amplifier conducts for what portion of the input signal cycle?
Advanced Components
Which amplifier class has the highest efficiency but the most distortion, making it suitable only for amplifying constant-amplitude signals such as FM or CW?
To amplify a single-sideband (SSB) signal with low distortion, an amplifier should be operated in:
In a common-emitter transistor amplifier, the purpose of the emitter bypass capacitor is to:
An oscillator requires which two basic conditions to sustain oscillation?
Compared with an LC oscillator, a crystal oscillator offers:
A variable frequency oscillator (VFO) used in a transmitter must above all be:
In a power supply, the component that converts AC into pulsating DC is the:
A full-wave rectifier produces a ripple frequency that is:
A Zener diode is commonly used in a power supply to:
Increasing the value of the filter capacitor in a power supply will generally:
An amplifier increases power from 5 watts to 50 watts. What is the power gain in decibels? (dB = 10*log10(Pout/Pin))
If the power into a feedline is reduced by 3 dB, the output power is approximately:
A signal is amplified by 6 dB. The output power is approximately how many times the input power?
In a push-pull amplifier using two transistors, a major advantage is:
The efficiency of an amplifier is defined as the ratio of:
A choke (inductor) used in a power supply filter opposes:
In a Colpitts oscillator, the feedback network uses:
The voltage regulation of a power supply describes:
A buffer amplifier is placed after an oscillator mainly to:
A signal level of 0 dBm corresponds to a power of:
Thermal runaway in a power transistor can be reduced by:
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