How Diodes Are Used Test From Gibilisco?
Gibilisco is a renowned author who write on on electronics and science. This quiz is based on his books and tests your about how diodes are used. This quiz contains various questions that not only tests your conceptual understanding but also provides you valuable information that would enhance you interests in the topic and would be great benefit in tests and revision. If you find the quiz helpful, do share it with your friends. All the best!
- 1.
When a diode is forward-biased, the anode voltage
- A.
Is negative relative to the cathode voltage
- B.
Is positive relative to the cathode voltage
- C.
Is the same as the cathode voltage
- D.
Alternates between positive and negative relative to the cathode voltage
Correct Answer
B. Is positive relative to the cathode voltageExplanation
When a diode is forward-biased, the anode voltage is positive relative to the cathode voltage. This means that the anode terminal of the diode is at a higher voltage compared to the cathode terminal. This forward biasing condition allows current to flow through the diode, as it reduces the barrier potential at the junction between the P-type and N-type semiconductor materials. In this configuration, the diode acts as a closed switch, allowing current to flow in the forward direction.Rate this question:
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- 2.
If a diode is connected in series with the secondary winding of an ac transformer, and if thepeak voltage across the diode never exceeds the avalanche voltage, then the output of the complete transformer-diode circuit is
- A.
Ac with half the frequency of the input
- B.
Ac with the same frequency as the input
- C.
Ac with twice the frequency of the input
- D.
None of the above
Correct Answer
D. None of the aboveExplanation
When a diode is connected in series with the secondary winding of an AC transformer, it acts as a rectifier, allowing current to flow in only one direction. The output of the circuit will be a pulsating DC waveform, not AC. Therefore, the correct answer is "none of the above" as none of the options mention a DC output.Rate this question:
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- 3.
A crystal set
- A.
Can be used to transmit radio signals
- B.
Requires a battery with long life
- C.
Requires no battery.
- D.
Is used for rectifying 60-Hz ac
Correct Answer
C. Requires no battery.Explanation
A crystal set is a simple radio receiver that uses the energy from the radio waves to power the circuit, eliminating the need for a battery. The crystal set relies on a crystal diode to rectify the radio frequency signal and convert it into audio signals that can be heard through a connected earphone or speaker. This design allows for a low-power and efficient radio reception without the need for an external power source like a battery.Rate this question:
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- 4.
A diode detector
- A.
Is used in power supplies
- B.
Is employed in some radio receivers
- C.
Is used to generate microwave RF signals
- D.
Changes dc into ac
Correct Answer
B. Is employed in some radio receiversExplanation
A diode detector is employed in some radio receivers because it is used to convert amplitude-modulated (AM) radio frequency signals into audio signals. This allows the receiver to demodulate and amplify the audio signal for the user to hear. The diode detector is able to extract the audio signal from the carrier wave by rectifying the signal, removing the negative half of the wave, and converting it into a pulsating direct current (DC) signal. This DC signal can then be further processed to produce the desired audio output.Rate this question:
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- 5.
If the output wave in a circuit has the same shape as the input wave, then
- A.
The circuit is operating in a linear manner
- B.
The circuit is operating as a frequency multiplier
- C.
The circuit is operating as a mixer
- D.
The circuit is operating as a rectifier
Correct Answer
A. The circuit is operating in a linear mannerExplanation
When the output wave in a circuit has the same shape as the input wave, it indicates that the circuit is operating in a linear manner. This means that the circuit is not distorting or altering the shape of the input wave. In a linear circuit, the output is directly proportional to the input, and there is no frequency multiplication, mixing, or rectification happening.Rate this question:
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- 6.
Suppose the two input signal frequencies to a mixer circuit are 3.522 MHz and 3.977 MHz.At which of the following frequencies can we expect a signal to exist at the output?
- A.
455 kHz
- B.
886 kHz
- C.
14.00 MHz
- D.
1.129 MHz
Correct Answer
A. 455 kHzExplanation
The mixer circuit combines two input signals and produces an output signal that is the sum and difference of the input frequencies. In this case, the input frequencies are 3.522 MHz and 3.977 MHz. To determine the frequencies at which a signal can exist at the output, we need to find the sum and difference of these frequencies. Adding the two frequencies gives us 7.499 MHz, which is not one of the options. However, subtracting the two frequencies gives us 0.455 MHz or 455 kHz, which is one of the options. Therefore, we can expect a signal to exist at the output frequency of 455 kHz.Rate this question:
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- 7.
Fill in the blanks to make the following sentence correct: “A spectrum analyzer provides adisplay of as a function of .”
- A.
Amplitude/time
- B.
Time/frequency
- C.
Frequency/time
- D.
Amplitude/frequency
Correct Answer
D. Amplitude/frequencyExplanation
A spectrum analyzer provides a display of amplitude as a function of frequency. This means that it shows the varying levels of amplitude for different frequencies in a signal.Rate this question:
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- 8.
Zener voltage is a specialized manifestation of
- A.
Forward breakover voltage
- B.
Peak forward voltage
- C.
Avalanche voltage
- D.
Reverse bias.
Correct Answer
C. Avalanche voltageExplanation
Zener voltage is a specialized manifestation of avalanche voltage. Avalanche voltage refers to the voltage at which the reverse-biased junction of a diode experiences a rapid increase in current due to the generation and acceleration of charge carriers. Zener voltage, on the other hand, specifically refers to the voltage at which a Zener diode begins to conduct in the reverse direction. Therefore, Zener voltage is a type of avalanche voltage that is specific to Zener diodes.Rate this question:
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- 9.
The forward breakover voltage of a silicon diode is
- A.
About 0.3 V
- B.
About 0.6 V
- C.
About 1.0 V
- D.
Dependent on the avalanche voltage
Correct Answer
B. About 0.6 VExplanation
The forward breakover voltage of a silicon diode is approximately 0.6 V. This is the voltage at which the diode starts conducting current in the forward direction. At voltages below 0.6 V, the diode is in the off state and does not allow current to flow. However, once the voltage exceeds 0.6 V, the diode turns on and allows current to pass through. The specific value of 0.6 V is a characteristic of silicon diodes and can vary slightly depending on the manufacturer and other factors.Rate this question:
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- 10.
A diode audio limiter circuit
- A.
Is useful for voltage regulation
- B.
Always uses Zener diodes
- C.
Rectifies the audio to reduce distortion
- D.
Can cause distortion under some conditions
Correct Answer
D. Can cause distortion under some conditionsExplanation
A diode audio limiter circuit can cause distortion under some conditions. This is because the diode limits the voltage of the audio signal, preventing it from exceeding a certain threshold. However, if the audio signal is already close to or exceeding this threshold, the diode can introduce distortion into the signal. This distortion occurs due to the non-linear characteristics of the diode, which can cause the signal to become distorted and altered. Therefore, while a diode audio limiter circuit is useful for voltage regulation, it can also introduce distortion under certain circumstances.Rate this question:
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- 11.
The capacitance of a varactor varies with the
- A.
Forward voltage
- B.
Reverse voltage
- C.
Avalanche voltage
- D.
Forward breakover voltage
Correct Answer
B. Reverse voltageExplanation
The capacitance of a varactor varies with the reverse voltage. A varactor is a type of diode that is designed to act as a voltage-controlled capacitor. When a reverse voltage is applied to the varactor, the width of the depletion region in the diode changes, resulting in a change in the capacitance. As the reverse voltage increases, the capacitance decreases, and vice versa. Therefore, the reverse voltage is the factor that determines the capacitance of a varactor.Rate this question:
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- 12.
The purpose of the I layer in a PIN diode is to
- A.
Minimize the junction capacitance
- B.
Optimize the avalanche voltage
- C.
Reduce the forward breakover voltage
- D.
Increase the current through the diode
Correct Answer
A. Minimize the junction capacitanceExplanation
The purpose of the I layer in a PIN diode is to minimize the junction capacitance. The I layer, also known as the intrinsic layer, is a lightly doped region between the P and N layers of the diode. By increasing the width of the I layer, the depletion region and the junction capacitance are reduced. This allows the diode to have a faster response time and lower signal distortion, making it suitable for high-frequency applications.Rate this question:
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- 13.
Which of these diode types can be used as the key element in the oscillator circuit of amicrowave radio transmitter?
- A.
A rectifier diode
- B.
A PIN diode
- C.
An IMPATT diode
- D.
None of the above
Correct Answer
C. An IMPATT diodeExplanation
An IMPATT diode can be used as the key element in the oscillator circuit of a microwave radio transmitter. IMPATT diodes are specially designed to generate high-frequency oscillations and are commonly used in microwave applications. They have a high-power output and are capable of operating at high frequencies, making them suitable for use in microwave radio transmitters. Rectifier diodes and PIN diodes do not have the same characteristics and capabilities as IMPATT diodes, so they are not suitable for this specific application.Rate this question:
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- 14.
A Gunnplexer is often used as a
- A.
Microwave communications device
- B.
Low-frequency RF detector
- C.
High-voltage rectifier
- D.
Signal mixer or frequency divider
Correct Answer
A. Microwave communications deviceExplanation
A Gunnplexer is a type of microwave communications device. It is commonly used for transmitting and receiving microwave signals in various applications such as radar, satellite communication, and wireless communication systems. It operates in the microwave frequency range, typically around 10 GHz, and uses a Gunn diode as the main component for generating and detecting microwave signals. The Gunnplexer's design and functionality make it suitable for long-distance and high-speed data transmission, making it an ideal choice for microwave communications.Rate this question:
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- 15.
The most likely place you would find an LED would be in
- A.
A rectifier circuit
- B.
A mixer circuit
- C.
A digital frequency display
- D.
An oscillator circuit
Correct Answer
C. A digital frequency displayExplanation
LEDs, or Light Emitting Diodes, are commonly used in digital frequency displays because they are efficient and can emit light in a specific color. LED displays are often used to show numerical values or symbols, making them suitable for digital frequency displays where the frequency value needs to be visually represented. LEDs are not typically found in rectifier circuits, mixer circuits, or oscillator circuits, as these circuits serve different purposes and do not require a visual display.Rate this question:
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- 16.
Coherent electromagnetic radiation is produced by a
- A.
Gunn diode
- B.
Varactor diode
- C.
Rectifier diode
- D.
Laser diode
Correct Answer
D. Laser diodeExplanation
A laser diode is capable of producing coherent electromagnetic radiation. Unlike other diodes mentioned, such as Gunn diode, varactor diode, and rectifier diode, a laser diode is specifically designed to emit a highly focused and coherent beam of light. This is achieved through the process of stimulated emission, where photons are produced in phase and at the same frequency, resulting in a concentrated and coherent output. Therefore, a laser diode is the correct answer for producing coherent electromagnetic radiation.Rate this question:
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- 17.
Suppose you want a circuit to operate in a stable manner when the load impedance varies.You might consider a coupling method that employs
- A.
A Gunn diode
- B.
An optoisolator
- C.
A photovoltaic cell
- D.
A PIN diode
Correct Answer
B. An optoisolatorExplanation
An optoisolator is a device that uses a combination of an LED and a phototransistor to provide electrical isolation between two circuits. It can be used to couple a circuit in such a way that it remains stable even when the load impedance varies. The optoisolator ensures that any changes in the load impedance do not affect the stability of the circuit by providing isolation between the input and output sides. This allows for reliable operation of the circuit regardless of variations in the load impedance.Rate this question:
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- 18.
The electrical power that a solar panel can provide in direct sunlight depends on all of thefollowing factors except
- A.
The ac voltage applied to the panel
- B.
The total surface area of all the cells in the panel
- C.
The angle at which the sunlight strikes the cells
- D.
The intensity of the sunlight that strikes the cells
Correct Answer
A. The ac voltage applied to the panelExplanation
The electrical power that a solar panel can provide in direct sunlight depends on the total surface area of all the cells in the panel, the angle at which the sunlight strikes the cells, and the intensity of the sunlight that strikes the cells. The AC voltage applied to the panel does not affect the power output of the solar panel.Rate this question:
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- 19.
Emission of energy in an IRED is caused by
- A.
High-frequency radio waves
- B.
Rectification
- C.
Changes in electron energy within atoms
- D.
None of the above.
Correct Answer
C. Changes in electron energy within atomsExplanation
The emission of energy in an IRED (Infrared Emitting Diode) is caused by changes in electron energy within atoms. When electrons in the atoms are excited to higher energy levels and then return to their original energy levels, they release energy in the form of infrared radiation. This process is known as electron transition and is responsible for the emission of energy in an IRED. High-frequency radio waves and rectification are not involved in this process.Rate this question:
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- 20.
A photodiode, when not used as a photovoltaic cell, has
- A.
Reverse bias
- B.
No bias
- C.
Forward bias
- D.
Negative resistance
Correct Answer
A. Reverse biasExplanation
A photodiode, when not used as a photovoltaic cell, is typically operated under reverse bias. This means that the p-side of the diode is connected to the negative terminal of the power supply, while the n-side is connected to the positive terminal. This configuration allows the photodiode to function as a light detector by creating a depletion region that separates the photogenerated electron-hole pairs. Under reverse bias, the electric field across the depletion region increases, enhancing the collection of these charge carriers. Therefore, reverse bias is the correct answer.Rate this question:
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Nov 16, 2023Quiz Edited by
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Dec 09, 2010Quiz Created by
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