intro
MCQs 1:
What is the process of converting alternating current into direct current known as?
Topic: Current Conversion in Electrical Systems
Correct Answer: C) Rectification
- The process of conversion from alternating current (AC) to direct current (DC) is known as rectification.
- Therefore, the correct answer is C, "Rectification."
MCQs 2:
In a half or full wave rectifier, how does the peak inverse voltage of the rectifier compare to the input voltage?
Topic: Rectification Process in Electrical Engineering
Correct Answer: B) It's less than the input voltage.
- The peak inverse voltage of a rectifier, whether half-wave or full-wave, is always less than the input voltage.
- This reduction in voltage is primarily due to the presence of diodes, which cut down the output voltage by approximately 0.7V.
- Therefore, the correct answer is B, "It's less than the input voltage."
MCQs 3:
Given a circuit with an input of an alternating sinusoidal wave, what would be the output?
Topic: Functionality of Electrical Circuits
Correct Answer: D) IV
- The provided circuit is a full wave rectifier, which converts an AC input to a DC output.
- The presence of a capacitor at the end of the circuit acts as a filter, smoothing out the waveform to produce the curve shown in IV.
- Hence, the correct answer is D, "IV."
Question 4:
If a half-wave rectifier has an input frequency of n Hz AC, what would its output be?
Topic: Fundamental Concepts in AC-DC Conversion
Correct Answer: C) n Hz pulsating DC
- A pulsating DC is a waveform that maintains a constant direction but may change in magnitude.
- For a half-wave rectifier with an input frequency of n Hz AC, the output frequency remains the same, producing an n Hz pulsating DC.
- Therefore, the correct answer is C, "n Hz pulsating DC."
Question 5:
What would be the state of resistance in an ideal diode when applied in reverse bias?
Topic: Characteristics of Ideal Diodes
Correct Answer: D) Infinite resistance
- An ideal diode is a conceptual model that simplifies the behavior of real diodes.
- When a diode is reverse-biased, it ideally blocks all current flow.
- This can be interpreted as the diode presenting infinite resistance to the circuit.
- Therefore, the correct answer is D, "Infinite resistance."
Question 6:
For a full wave rectifier with an input frequency of 50Hz, what is the frequency of the ripple in the output?
Topic: Full Wave Rectification Process
Correct Answer: C) 100Hz
- Full wave rectification is a process where both half cycles (positive and negative) of the AC input signal are allowed to pass through.
- The frequency of the ripple in the output is twice the input frequency.
- For an input frequency of 50Hz, the ripple frequency would be 2*50 = 100Hz.
- Hence, the correct answer is C, "100Hz."
Question 7:
What is the required number of diodes for a bridge rectifier?
Topic: Structure of Bridge Rectifiers
Correct Answer: D) 4
- A bridge rectifier is a circuit used to convert AC to DC and requires four or more diodes.
- It ensures that the output polarity is the same for any input polarity.
- So, the correct answer is D, "4."
Question 8:
Assuming a half-wave rectifier and a full-wave rectifier both have an input frequency of 50Hz, what would their output frequencies be respectively?
Topic: Frequency Output of Rectifiers
Correct Answer: A) 50Hz, 100Hz
- Half-wave rectification retains the input frequency, which is 50Hz in this case.
- Full-wave rectification effectively doubles the output frequency, making it 100Hz.
- So, the correct answer is A, "50Hz, 100Hz".
Question 9:
What is one of the main functions of a diode in an electronic circuit?
Topic: Roles of Diodes in Electronic Circuits
Correct Answer: C) Rectification
- A diode's primary function is to allow current to flow in one direction, enabling rectification (conversion of AC to DC).
- It achieves this by allowing only one half of the AC waveform to pass through.
- Therefore, the correct answer is C, "Rectification".
Question 10:
What is the power efficiency of a half-wave rectifier?
Topic: Rectifier Efficiency
Correct Answer: C) 40.6%
- The efficiency of a rectifier relates to its ability to convert AC to DC.
- For a half-wave rectifier, this efficiency is 40.6%.
- This is because it only uses half of the input wave, leading to a lot of power wastage.
- Hence, the correct answer is C, "40.6%".
Question 11:
For a half-wave rectifier with an input frequency of 100Hz, what would be the frequency of the ripple?
Topic: Half-Wave Rectifier Frequency
Correct Answer: C) 100Hz
- A half-wave rectifier operates by only allowing one half of an AC waveform to pass through to the output.
- Therefore, the frequency of the ripple, or the repeating pattern observed in the output, is identical to the input frequency.
- In this instance, with an input frequency of 100Hz, the ripple frequency is also 100Hz.
- Hence, the correct answer is C, "100Hz."
Question 12:
In relation to a P-N junction diode that is not connected to any circuit, which statement is true?
Topic: P-N Junction Diode
Correct Answer: C) An electric field exists at the junction, pointing from the N-type side to the P-type side.
- A P-N junction diode, even when not connected to a circuit, maintains an electric field.
- This electric field is created due to the difference in charge carriers between the P-type and N-type materials that form the diode.
- The field direction is from the negatively charged N-type side towards the positively charged P-type side.
- Therefore, the correct answer is C, "An electric field exists at the junction, pointing from the N-type side to the P-type side."
MCQs 13:
Which of the following best describes the function of a diode?
Topic: Diode Function
Correct Answer: D) None of the above.
- Diodes have a variety of applications, but they are most commonly used as rectifiers.
- A rectifier is a type of circuit that converts alternating current (AC) into direct current (DC).
- This function of a diode is not reflected in options A, B, or C.
- As a result, the correct answer is D, "None of the above."
MCQs 14:
What is the primary application of a PN junction diode?
Topic: PN Junction Diode
Correct Answer: A) As a rectifier.
- The PN junction diode is a versatile electronic component with various applications.
- Its main function, however, is to serve as a rectifier.
- Rectifiers are used to convert alternating current (AC) into direct current (DC).
- Therefore, the correct answer is A, "As a rectifier."
MCQs 15:
What is the efficiency of a center tapped full-wave rectifier?
Topic: Rectifier Efficiency
Correct Answer: D) 81.2%
- Rectifier efficiency is a measure of its effectiveness in converting AC to DC.
- This is calculated by taking the ratio of the DC power output to the maximum AC power delivered to the load, and is usually expressed as a percentage.
- For center tapped full-wave rectifiers, this efficiency is 81.2%.
- Hence, the correct answer is D, "81.2%."
MCQ 16:
What type of rectifier uses 2 diodes?
Topic: Rectifiers
Correct Answer: C) Full-wave rectifier.
- The type of rectifier is determined by the number of diodes it uses and how they are configured.
- A full-wave rectifier requires at least 2 diodes.
- These diodes are arranged in such a way that when one diode is forward-biased, the other is reverse-biased.
- As a result, the correct answer is C, "Full-wave rectifier."
MCQ 17:
What is the peak inverse voltage on a diode given a peak voltage of 5V on a center-tapped full-wave rectifier circuit and a diode cut-in voltage of 0.7V?
Topic: Diode Characteristics - Peak Inverse Voltage
Correct Answer: B) 9.3V
- Peak inverse voltage (PIV) in a rectifier is a crucial parameter, which signifies the maximum negative voltage a diode can withstand.
- It is typically calculated as PIV = 2Vm - Vd.
- Here, Vm is the peak voltage (5V in this case) and Vd is the diode cut-in voltage (0.7V here).
- By substituting the given values into the equation, we obtain PIV = 9.3V.
- Thus, the correct answer is B, "9.3V."
MCQ 18:
What is the average output direct current value in a half-wave rectifier?
Topic: Half-Wave Rectifier - Average Output Current
Correct Answer: A) Io/π
- In a half-wave rectifier, the average output direct current is a key quantity.
- It is defined as the average value of current over a cycle divided by 2.
- Mathematically, it can be represented as (2Io/2π).
- Simplifying the above expression, we get Io/π.
- Therefore, the correct answer is A, "Io/π."
MCQs 19:
For which type of rectifier can a bridge rectifier serve as a substitute?
Topic: Rectifiers
Correct Answer: A) Full wave rectifier
- A bridge rectifier is a particular type of rectifier that uses four diodes in a bridge arrangement to achieve full-wave rectification.
- It is considered superior to a full-wave rectifier due to its ability to convert both halves of an AC waveform to pulsating DC.
- Therefore, a bridge rectifier is an excellent alternative for a full-wave rectifier.
- Hence, the correct answer is A, "Full wave rectifier."
MCQs 20:
What would be the ripple frequency of a full-wave rectifier if the input frequency is 50Hz?
Topic: Full-Wave Rectification
Correct Answer: A) 100Hz
- Ripple frequency is an important aspect of a full-wave rectifier, as it directly relates to the consistency of the rectified output.
- It is generally double the input frequency in a full-wave rectifier.
- Given that the input frequency in this scenario is 50Hz, the ripple frequency will be 2 * 50Hz = 100Hz.
- Therefore, the correct answer is A, "100Hz."
MCQs 21:
What effect does half-wave rectification have on the frequency of a wave?
Topic: Rectification and Wave Frequency
Correct Answer: D) Remains same
- Half-wave rectification implies the conversion of one-half of the input AC signal into a DC signal.
- It does not modify the frequency of the wave; rather, it maintains the same frequency as the input signal.
- Full rectification, on the other hand, doubles the frequency.
- As such, the correct response is D, "Remains same."
MCQs 22:
Under what conditions does a P-N junction diode perform as an insulator?
Topic: P-N Junction Diode
Correct Answer: C) When reverse-biased
- The behavior of a P-N junction diode depends on its biasing condition.
- When the diode is forward-biased, it conducts current, acting as a conductor.
- However, when the diode is reverse-biased, it blocks current flow, thus acting as an insulator.
- Therefore, the correct answer is C, "When reverse-biased."
MCQs 23:
In a full-wave rectifier, how is the biasing of the two diodes set at a given instance?
Topic: Full-Wave Rectifier
Correct Answer: A) One is forward-biased while the other is reverse-biased
- In a full-wave rectifier circuit, two diodes are used to convert the entire input signal into a DC output.
- The diodes are set up such that when one is in a forward-biased state, the other is in a reverse-biased state.
- This configuration ensures the conversion of both halves of the AC input into DC output.
- Therefore, the correct answer is A, "One is forward-biased while the other is reverse-biased."
MCQs 24:
What is the transformer utilization factor for a center-tapped full-wave rectifier?
Topic: Transformer Utilization Factor (TUF)
Correct Answer: C) 0.693
- The transformer utilization factor (TUF) is a measure of how effectively a transformer is used by a rectifier.
- It is defined as the ratio of the AC power delivered to the load to the DC power rating of the transformer.
- For a center-tapped full-wave rectifier, the TUF is typically around 0.693.
- Therefore, the correct answer is C, "0.693."