Oscillator MCQ Quiz With Answers
Do you know about an electronic oscillator? What is the role of the oscillator? Can you attempt these MCQ questions by providing the correct answers in the quiz below? An oscillator is an electronic circuit that works on the oscillation principle and i.e., a circuit that produces continuous, repeated, and alternating waveforms. Here, we give you an interesting way of evaluating your electronics knowledge. Doesn't it sound cool? What else do you need? Take this test and learn more about oscillators.
- 1.
The decibel is a unit of
- A.
Relative signal strength
- B.
Voltage
- C.
Power
- D.
Current
Correct Answer
A. Relative signal strengthExplanation
The decibel is a unit used to measure the relative signal strength. It is commonly used in telecommunications and audio systems to quantify the difference in power between two signals. The decibel scale allows for a logarithmic representation of signal strength, making it easier to compare and analyze different signal levels. Therefore, the correct answer is "relative signal strength."Rate this question:
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- 2.
An oscillator at RF requires the use of
- A.
A common drain or common collector circuit
- B.
A stage with gain
- C.
A tapped coil
- D.
A quartz crystal
Correct Answer
B. A stage with gainExplanation
An oscillator at RF requires the use of a stage with gain because an oscillator is a device that generates a continuous output signal without any input signal. In order to sustain oscillation, the circuit needs to provide positive feedback, which is achieved by having a stage with gain. The gain in the circuit compensates for any losses and ensures that the output signal is continuously amplified and fed back to the input, resulting in the desired oscillation. The other options, such as a common drain or common collector circuit, a tapped coil, or a quartz crystal, are not essential components for generating oscillation in an RF oscillator circuit.Rate this question:
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- 3.
Suppose a circuit is found to have a gain figure of −15 dB. Which of the following statementsis true?
- A.
The output signal is stronger than the input signal.
- B.
The input signal is stronger than the output signal.
- C.
The input signal is 15 times as strong as the output signal.
- D.
The output signal is 15 times as strong as the input signal.
Correct Answer
B. The input signal is stronger than the output signal.Explanation
A gain figure of -15 dB indicates a decrease in signal strength. dB is a logarithmic scale, so a negative value means a decrease in magnitude. Therefore, the output signal is weaker than the input signal, making the statement "The input signal is stronger than the output signal" true.Rate this question:
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- 4.
In an oscillator circuit, the feedback should be
- A.
As great as possible
- B.
Kept to a minimum
- C.
Just enough to sustain oscillation
- D.
Done through a transformer whose wires can be switched easily
Correct Answer
C. Just enough to sustain oscillationExplanation
In an oscillator circuit, the feedback should be just enough to sustain oscillation. This means that the amount of feedback should be carefully controlled so that it provides the necessary energy to maintain oscillation without causing instability or damping. Too much feedback can lead to over-amplification and distortion, while too little feedback can result in insufficient energy to sustain oscillation. Therefore, finding the right balance of feedback is crucial for the proper functioning of an oscillator circuit.Rate this question:
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- 5.
A power gain of 44 dB is equivalent to which of the following output/input power ratios?
- A.
44:1
- B.
160:1
- C.
440:1
- D.
25,000:1
Correct Answer
D. 25,000:1Explanation
A power gain of 44 dB means that the output power is 25,000 times greater than the input power. This can be calculated by using the formula: Power Gain (in dB) = 10 * log10(Output Power/Input Power). In this case, 44 = 10 * log10(Output Power/Input Power), which can be rearranged to find that the Output Power/Input Power ratio is 25,000:1.Rate this question:
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- 6.
An RF choke
- A.
Passes RF signals but blocks dc
- B.
Passes both RF signals and dc
- C.
Passes dc but blocks RF signals
- D.
Blocks both dc and RF signals
Correct Answer
C. Passes dc but blocks RF signalsExplanation
An RF choke is a type of inductor that is designed to block high-frequency signals (RF signals) while allowing direct current (dc) to pass through. This is achieved by using a coil of wire to create a magnetic field that opposes the flow of RF signals, effectively blocking them. However, since direct current does not change in frequency, it is not affected by the magnetic field and can pass through the choke. Therefore, an RF choke passes dc but blocks RF signals.Rate this question:
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- 7.
The optimum capacitance values in an amplifier circuit depend on
- A.
The power-supply voltage
- B.
The power-supply polarity
- C.
The input signal strength
- D.
The input signal frequency
Correct Answer
D. The input signal frequencyExplanation
The optimum capacitance values in an amplifier circuit depend on the input signal frequency. This is because different frequencies require different amounts of capacitance to achieve optimal performance. Higher frequencies typically require smaller capacitance values, while lower frequencies require larger capacitance values. By selecting the appropriate capacitance values for the input signal frequency, the amplifier circuit can effectively amplify the desired frequency range and minimize distortion or loss of signal quality.Rate this question:
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- 8.
An oscillator might fail to start for any of the following reasons, except
- A.
Low battery voltage
- B.
Low stage gain
- C.
In-phase feedback
- D.
A high-impedance load
Correct Answer
C. In-phase feedbackExplanation
In-phase feedback is not a reason for an oscillator to fail to start. In fact, feedback is necessary for an oscillator to sustain oscillations. It provides the necessary positive feedback to compensate for energy losses and maintain the desired oscillation frequency. Therefore, in-phase feedback is not an exception and cannot be a reason for an oscillator to fail to start.Rate this question:
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- 9.
In which of the following FET amplifier types does drain current flow for exactly 50 percentof the signal cycle?
- A.
Class A
- B.
Class AB1
- C.
Class AB2
- D.
Class B
Correct Answer
D. Class BExplanation
In a Class B FET amplifier, the drain current flows for exactly 50 percent of the signal cycle. This is because in Class B amplifiers, the FET conducts current only when the input signal exceeds a certain threshold, typically around zero volts. This means that the FET is only active during half of the input signal cycle, resulting in a drain current flow of 50 percent.Rate this question:
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- 10.
The frequency at which a quartz crystal oscillator produces energy is largely dependent on
- A.
The load impedance
- B.
The physical thickness of the quartz wafer
- C.
The amount of resistance through the crystal
- D.
The power-supply voltage
Correct Answer
B. The physical thickness of the quartz waferExplanation
The frequency at which a quartz crystal oscillator produces energy is largely dependent on the physical thickness of the quartz wafer. The thickness of the wafer determines the resonant frequency of the crystal, as it affects the speed at which the crystal vibrates. A thicker wafer will vibrate at a lower frequency, while a thinner wafer will vibrate at a higher frequency. Therefore, the physical thickness of the quartz wafer directly influences the frequency produced by the oscillator.Rate this question:
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- 11.
Which bipolar amplifier type has some distortion in the signal wave, with collector currentduring most, but not all, of the cycle?
- A.
Class A
- B.
Class AB1
- C.
Class AB2
- D.
Class B
Correct Answer
C. Class AB2Explanation
Class AB2 amplifiers have some distortion in the signal wave because the collector current is present during most, but not all, of the cycle. In Class AB2 amplifiers, the active device conducts for more than half of the input cycle, but less than the full cycle. This results in some distortion in the signal wave. Class AB2 amplifiers are commonly used in audio applications where moderate distortion is acceptable, such as in power amplifiers for music systems.Rate this question:
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- 12.
An RF oscillator usually
- A.
Produces an output signal with an irregular wave shape
- B.
Has most or all of its energy at a single frequency
- C.
Produces a sound that depends on its waveform
- D.
Employs an RC circuit to determine the output amplitude
Correct Answer
B. Has most or all of its energy at a single frequencyExplanation
An RF oscillator usually has most or all of its energy at a single frequency. This means that the oscillator generates a signal that is concentrated at a specific frequency, rather than being spread out across a range of frequencies. This is important in RF (radio frequency) applications, where a specific frequency is desired for communication or transmission purposes. By having most of its energy at a single frequency, the RF oscillator can provide a stable and reliable signal for these applications.Rate this question:
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- 13.
A class C amplifier can be made linear by
- A.
Reducing the bias
- B.
Increasing the drive
- C.
Using two transistors in push-pull
- D.
No means; a class C amplifier is always nonlinear
Correct Answer
D. No means; a class C amplifier is always nonlinearExplanation
A class C amplifier is always nonlinear because it operates with less than 50% of the input signal cycle. This means that it does not reproduce the entire input waveform accurately, resulting in distortion. Regardless of any adjustments or modifications, a class C amplifier cannot be made linear.Rate this question:
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- 14.
A frequency synthesizer has
- A.
High power output
- B.
High frequency drift rate
- C.
Exceptional stability
- D.
An adjustable wave shape
Correct Answer
C. Exceptional stabilityExplanation
A frequency synthesizer is a device used to generate precise and stable frequencies. It is important for the synthesizer to maintain stability in order to ensure accuracy and reliability in frequency generation. This stability allows the synthesizer to produce consistent and reliable output frequencies over time, without significant variations or drift. This is crucial in various applications such as telecommunications, radar systems, and scientific research, where precise and stable frequencies are required for proper functioning. Therefore, the exceptional stability of a frequency synthesizer is a desirable characteristic that sets it apart from other devices.Rate this question:
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- 15.
A graphic equalizer is a form of
- A.
Bias control for an NPN bipolar transistor
- B.
Gain control for an RF oscillator
- C.
Tone control that can be used in an audio amplifier
- D.
Circuit for adjusting the waveform of an RF oscillator
Correct Answer
C. Tone control that can be used in an audio amplifierExplanation
A graphic equalizer is a device that allows users to adjust the tone of audio signals in an amplifier. It consists of multiple bands, each representing a specific frequency range, which can be individually adjusted to boost or attenuate the corresponding frequencies. This allows users to shape the overall sound by emphasizing or reducing certain frequencies. Therefore, the given answer accurately describes the function of a graphic equalizer as a tone control that can be used in an audio amplifier.Rate this question:
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- 16.
If the impedance of the load connected to the output of an oscillator is extremely high,
- A.
The frequency will drift excessively
- B.
The power output will be reduced
- C.
The oscillator might fail to start
- D.
It is no cause for concern; in fact, it is a good thing.
Correct Answer
D. It is no cause for concern; in fact, it is a good thing.Explanation
If the impedance of the load connected to the output of an oscillator is extremely high, it is no cause for concern; in fact, it is a good thing. This is because a high load impedance ensures that the oscillator is isolated from the load, preventing any unwanted interactions or disturbances. It allows the oscillator to operate independently and maintain its stability, without being affected by the load. Therefore, a high load impedance is desirable in this scenario.Rate this question:
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- 17.
Suppose a certain bipolar-transistor PA is 66 percent efficient. The output power is 33 W.The dc collector power input is
- A.
22 W
- B.
50 W
- C.
2.2 W
- D.
Impossible to determine without more information
Correct Answer
B. 50 WExplanation
Since the bipolar-transistor PA is 66 percent efficient, it means that 66 percent of the input power is converted into output power. Therefore, to find the dc collector power input, we can divide the output power by the efficiency percentage. In this case, 33 W divided by 0.66 (66 percent as a decimal) equals 50 W. Hence, the correct answer is 50 W.Rate this question:
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- 18.
A tuned RF PA must always be
- A.
Set to work over a wide range of frequencies
- B.
Adjusted for maximum power output
- C.
Operated at an even harmonic of the input frequency
- D.
Operated in class C
Correct Answer
B. Adjusted for maximum power outputExplanation
A tuned RF PA must be adjusted for maximum power output because this ensures that the power amplifier is operating at its highest efficiency and delivering the maximum amount of power to the load. By adjusting the PA for maximum power output, the system can achieve optimal performance and transmit signals with the highest possible power level. This is important in applications where high power transmission is required, such as in wireless communication systems or broadcasting.Rate this question:
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- 19.
Class B amplification can be used to obtain low distortion for audio applications
- A.
By connecting two amplifiers in cascade, thereby maximizing the gain and generating a pure sine wave output.
- B.
By biasing the bipolar transistor or FET beyond cutoff or pinchoff, thereby ensuring that the output is in phase with the input.
- C.
By connecting two identical bipolar transistors or FETs, biased exactly at cutoff or pinchoff, in a push-pull configuration.
- D.
By biasing the bipolar transistor or FET in the middle of the straight-line portion of the characteristic curve.
Correct Answer
C. By connecting two identical bipolar transistors or FETs, biased exactly at cutoff or pinchoff, in a push-pull configuration.Explanation
Class B amplification is a technique used to minimize distortion in audio applications. By connecting two identical bipolar transistors or FETs in a push-pull configuration, both transistors are biased exactly at cutoff or pinchoff, ensuring that each transistor operates in its active region for half of the input waveform. This configuration allows for efficient power utilization and eliminates the need for a biasing voltage, resulting in a pure sine wave output with low distortion.Rate this question:
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Current Version
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Sep 06, 2023Quiz Edited by
ProProfs Editorial Team -
Dec 09, 2010Quiz Created by
BATANGMAGALING
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