intro
MCQs 1:
Which device is used for the conversion of A.C to D.C?
Topic: Conversion of Alternating Current to Direct Current
Correct Answer: B) Rectifier
- The process of conversion from A.C (Alternating Current) to D.C (Direct Current) is accomplished by a specific device.
- Among the given options, a "rectifier" serves this purpose by allowing current to flow in only one direction, thereby converting A.C to D.C.
- Therefore, the correct answer is B, "Rectifier".
MCQs 2:
What is the fundamental frequency in the ripple for a half wave rectifier circuit functioning from a 50Hz source?
Topic: Fundamental Frequency in Half Wave Rectification
Correct Answer: B) 50 Hz
- For a half wave rectifier, the fundamental frequency relies on the time interval between the two peaks, which remains constant even though the negative wave part is snipped off.
- Thus, the frequency or period of the ripple matches the source frequency, in this case, 50 Hz.
- As a result, the correct answer is B, "50 Hz".
MCQs 3:
A bridge rectifier is classified as:
Topic: Bridge Rectifiers in Electronics
Correct Answer: A) Full wave rectifier
- Bridge rectifiers are distinguished by their construction, which includes a Wheatstone bridge and 4 diodes arranged in the same direction, making it a full wave rectifier.
- Half wave rectifiers, on the other hand, are built with a single diode and a center tap transformer with diodes facing opposite directions.
- Consequently, the correct answer is A, "Full wave rectifier".
Question 4:
A half wave rectifier permits which cycles into positive cycles?
Topic: Cycle Passage in Half Wave Rectifiers
Correct Answer: C) Either upper or lower cycles
- The functioning of a half wave rectifier allows either a positive or negative half cycle to pass, unlike a full wave rectifier that allows both.
- This means that it can permit either upper or lower cycles to turn into positive cycles.
- Therefore, the correct answer is C, "Either upper or lower cycles".
Question 5:
Which statement best describes the operation of diodes in a full-wave rectifier?
Topic: Diode Function in Full Wave Rectification
Correct Answer: A) In a full-wave rectifier, one diode conducts current in one half cycle, and the other diode conducts in the other half cycle.
- Full-wave rectification involves the use of two diodes, but they don't operate simultaneously.
- Instead, one diode conducts electricity in one half cycle, while the other diode conducts in the other half cycle.
- Thus, the correct answer is A, "In a full-wave rectifier, one diode conducts current in one half cycle, and the other diode conducts in the other half cycle."
Question 6:
What is the approximate efficiency of a Half Wave rectifier?
Topic: Efficiency of Half Wave Rectifiers
Correct Answer: C) 40%
- The efficiency of a half-wave rectifier is calculated using the formula 4/π^2.
- Following this formula, we find that the efficiency is 0.40, or 40%.
- Therefore, the correct answer is C, "40%".
MCQs 7:
A center tap transformer used for complete rectification of alternating current employs:
Topic: Transformer Utilization in Full Rectification
Correct Answer: A) 2 diodes in the same direction
- For the complete rectification of alternating current, a center tap transformer is used.
- In this setup, two diodes in the same direction are used, ensuring full rectification.
- Hence, the correct answer is A, "2 diodes in the same direction".
MCQs 8:
In a given circuit, what will be the practical current value through the resistor?
Topic: Current Flow in a Resistor Circuit
Correct Answer: D) None of the above
- In the given circuit, the diode's orientation is in reverse bias, implying a resistance to current flow.
- As a result, no current can pass through the circuit, including the resistor.
- Consequently, the correct answer is D, "None of the above".
MCQs 9:
What is the ripple factor of a half-wave rectifier?
Topic: Half-Wave Rectifier Ripple Coefficient
Correct Answer: A) 1.21
- The ripple factor is a measure of the effectiveness of a rectifier in converting AC into DC.
- It is defined as the ratio of the root mean square (rms) value of the AC component to the DC component.
- For a half-wave rectifier, the ripple factor is 1.21, which is the correct answer (option A).
Question 10:
What does a 50V rating on a Zener diode imply?
Topic: Understanding the Rating of a Zener Diode
Correct Answer: C) It permits current of 50V and above when in reverse bias.
- A Zener diode is unique in that it can allow current to pass in reverse bias beyond a certain voltage threshold.
- If a Zener diode is rated 50V, it implies that if the reverse potential exceeds 50V, it will allow the current to flow.
- Therefore, the correct answer is C, "It permits current of 50V and above when in reverse bias."
Question 11:
If the peak voltage for a full-wave rectifier reads 20V, what would be the value of Vrms?
Topic: Calculating Vrms in a Full-Wave Rectifier
Correct Answer: B) 14.14 V
- In a full-wave rectifier, the relationship between the peak voltage (Vmax) and the rms voltage (Vrms) is defined by the formula Vrms = Vmax/√2.
- Applying this formula with a Vmax of 20V, we calculate Vrms as 20/√2 = 14.14V.
- Thus, the correct answer is B, "14.14 V".
Question 12:
If a bulb attached to an AC source achieves maximum brightness 100 times each second, how often will it reach maximum brightness when connected to a rectified DC source via a Wheatstone circuit?
Topic: Impact of Rectification on Bulb Brightness Frequency
Correct Answer: C) 100 times
- With an AC source, a bulb reaches its maximum brightness twice per wave, during both the positive and negative cycles.
- When the AC is fully rectified (as in a Wheatstone circuit), the number of maximum brightness incidents remains the same.
- Therefore, the correct answer is C, "100 times".
MCQs 13:
Given a full-wave rectifier circuit powered by a 50Hz mains supply, what would be the fundamental frequency of the ripple?
Topic: Frequency of Ripple in a Full-Wave Rectifier
Correct Answer: D) 100 Hz
- The output frequency in a full-wave rectifier is double the input frequency because it produces output for both the positive and negative cycles of the input AC.
- Therefore, if the input frequency is 50Hz, the frequency of the ripple in the output would be 2 x 50Hz = 100Hz.
- Consequently, the correct answer is D, "100 Hz".
MCQs 14:
How would you describe the total charge associated with an N-type material?
Topic: Determining the Net Charge of an N-Type Material
Correct Answer: D) 0
- An N-type material is created when neutral atoms are subjected to doping, resulting in extra electrons in the material.
- Despite the increase in electron count, the overall neutrality of the material remains preserved, meaning there's no net charge.
- Therefore, the correct answer is D, "0".
MCQs 15:
Identify the item that does not classify as a form of rectifier:
Topic: Recognizing Types of Rectifiers
Correct Answer: A) Phase wave rectifier
- Rectifiers are primarily used to convert alternating current (AC) to direct current (DC) and comprise of types such as full-wave and half-wave rectifiers.
- A 'phase wave rectifier' does not exist in the realm of electronics, making it the incorrect option.
- Thus, the correct answer is A, "Phase wave rectifier".
Question 16:
Assuming a 50Hz alternating current is rectified using a configuration of four diodes, what frequency would the resultant direct current exhibit?
Topic: Determining Rectified Current Frequency with Four Diodes
Correct Answer: B) 100Hz
- The presence of four diodes indicates a full-wave rectifier configuration, which doubles the frequency of the input AC.
- Therefore, for an input frequency of 50Hz, the output DC frequency after full-wave rectification would be 2 x 50Hz = 100Hz.
- Consequently, the correct answer is B, "100Hz".
Question 17:
What is the frequency of the output current in a full-wave rectifier, if the frequency of the input AC current is represented by 'v'?
Topic: Output Frequency in a Full-Wave Rectifier
Correct Answer: C) 2v
- A full-wave rectifier effectively doubles the frequency of the input AC because it configures the current for both the positive and negative cycles of the input.
- If 'v' is the frequency of the input AC, the output frequency would be 2v.
- Consequently, the correct answer is C, "2v".
Question 18:
A p−n junction diode (D) is used as a rectifier in the circuit diagram below, which is connected to an alternating current source (V). Which option best illustrates the current in the resistor (R)?
Topic: Current in a Resistor Connected to a PN Junction Diode
Correct Answer: C) Option C
- A rectifier circuit, like the one in the question, uses a p−n junction diode to convert AC to DC.
- This DC current is then shown in the graph as a wave that only exists in the positive y-axis, since it only allows for current flow in one direction.
- Therefore, the correct graph representation of the current in the resistor (R) would be the one shown in Option C.
MCQs 20:
What is the minimum quantity of diodes necessary for total conversion of AC into DC using a Bridge Rectifier?
Topic: Diode Count in a Bridge Rectifier for Full AC to DC Conversion
Correct Answer: D) 4
- A bridge rectifier is a circuit used to convert full-wave AC to DC and typically requires four diodes.
- Therefore, the correct answer is D, "4".
MCQs 21:
What is the efficiency level of a full-wave rectifier?
Topic: Efficiency of a Full-Wave Rectifier
Correct Answer: D) 80.6%
- Efficiency in a full-wave rectifier is about 80.6%, which is higher than a half-wave rectifier's efficiency.
- So, the correct answer is D, "80.6%".
MCQs 22:
What kind of electrical circuit is utilized to achieve a smooth DC current from a rectified output?
Topic: Circuit Type for Achieving Smooth DC from a Rectified Output
Correct Answer: C) Filter
- To smooth out the DC output from a rectifier, a filter circuit is used.
- A filter reduces ripple in the rectified output, providing a stable DC current.
- Therefore, the correct answer is C, "Filter".