Q.1 What type of rectifier uses only one diode and allows current to flow in one direction only?
Full-wave rectifier
Half-wave rectifier
Bridge rectifier
Three-phase rectifier
Explanation - A half-wave rectifier uses a single diode to allow only one half of the AC sine wave to pass through, blocking the other half.
Correct answer is: Half-wave rectifier
Q.2 In a full-wave bridge rectifier, how many diodes are typically used?
2
3
4
6
Explanation - A full-wave bridge rectifier consists of four diodes arranged to convert both halves of the AC waveform into DC.
Correct answer is: 4
Q.3 Which of the following is a benefit of a full-wave bridge rectifier over a half-wave rectifier?
Higher ripple factor
Lower output voltage
Higher average DC voltage
Requires fewer components
Explanation - Full-wave rectifiers produce a higher average DC voltage because both halves of the input AC waveform are utilized.
Correct answer is: Higher average DC voltage
Q.4 What is the formula for the average output voltage of an ideal full-wave bridge rectifier without a filter capacitor?
Vavg = Vpeak / π
Vavg = Vpeak
Vavg = 2Vpeak / π
Vavg = Vpeak / 2
Explanation - The average output of an ideal full-wave bridge rectifier is (2*Vpeak)/π, derived from integrating the rectified sine wave over a period.
Correct answer is: Vavg = 2Vpeak / π
Q.5 Which component is commonly used to reduce the ripple voltage in a rectifier circuit?
Resistor
Inductor
Capacitor
Transistor
Explanation - A smoothing capacitor is placed across the DC output to store charge during peaks and supply current during troughs, reducing ripple.
Correct answer is: Capacitor
Q.6 In a single-phase full-wave bridge rectifier, what happens to the output voltage when the input voltage is doubled?
It quadruples
It remains the same
It doubles
It halves
Explanation - The output voltage of a rectifier is directly proportional to the input RMS voltage; doubling the input doubles the output.
Correct answer is: It doubles
Q.7 Which of the following is NOT a characteristic of a rectifier circuit?
Converts AC to DC
Produces zero ripple
Requires diodes
Has a forward voltage drop
Explanation - All practical rectifiers produce some ripple; perfect DC without ripple is impossible without additional filtering.
Correct answer is: Produces zero ripple
Q.8 What does the term 'ripple factor' refer to in the context of rectified DC?
The ratio of peak to RMS voltage
The ratio of AC ripple voltage to DC voltage
The maximum voltage drop across a diode
The frequency of the ripple signal
Explanation - Ripple factor is defined as Vripple (RMS) divided by Vdc, indicating how smooth the DC output is.
Correct answer is: The ratio of AC ripple voltage to DC voltage
Q.9 Which rectifier topology is most suitable for high-current applications?
Half-wave rectifier
Full-wave bridge rectifier
Single-diode rectifier
Three-phase rectifier
Explanation - The full-wave bridge uses all four diodes to share current, reducing the peak current per diode and allowing higher total currents.
Correct answer is: Full-wave bridge rectifier
Q.10 Which of the following components is most critical to protect a rectifier from excessive reverse voltage?
Capacitor
Zener diode
Inductor
Resistor
Explanation - A Zener diode can clamp the reverse voltage to a safe level, preventing diode breakdown.
Correct answer is: Zener diode
Q.11 What is the main function of a flyback converter in power electronics?
To convert DC to AC
To step up or step down DC voltage
To smooth ripple in AC circuits
To increase power factor in AC systems
Explanation - A flyback converter is a type of DC-DC converter that uses a transformer to provide isolated voltage conversion.
Correct answer is: To step up or step down DC voltage
Q.12 In a buck converter, what does the duty cycle (D) represent?
The ratio of output voltage to input voltage
The ratio of the on-time of the switch to the total switching period
The ratio of the output current to the input current
The ratio of the switching frequency to the ripple current
Explanation - Duty cycle is defined as D = Ton / T, determining how long the switch conducts during each cycle.
Correct answer is: The ratio of the on-time of the switch to the total switching period
Q.13 Which topology is used to achieve a negative output voltage relative to the input?
Boost converter
Buck converter
Inverting converter (buck-boost)
Flyback converter
Explanation - A buck-boost converter can produce an output voltage that is either higher or lower than the input, and can be inverted.
Correct answer is: Inverting converter (buck-boost)
Q.14 What is the primary advantage of a synchronous rectifier compared to an ordinary rectifier in a DC-DC converter?
Higher output voltage
Lower conduction losses
Higher ripple factor
Simpler control circuitry
Explanation - Synchronous rectifiers replace diodes with MOSFETs that have lower forward voltage drops, reducing power dissipation.
Correct answer is: Lower conduction losses
Q.15 Which component is critical to filter the output of a half-wave rectifier to achieve a smoother DC voltage?
Capacitor
Diode
Resistor
Transistor
Explanation - A capacitor across the load smooths out the pulsating DC from a half-wave rectifier, reducing voltage variations.
Correct answer is: Capacitor
Q.16 A full-wave bridge rectifier produces a ripple frequency that is how many times higher than the AC input frequency?
Same as input
Double the input
Half the input
Triple the input
Explanation - The bridge rectifier uses both halves of the AC cycle, producing ripple at twice the mains frequency.
Correct answer is: Double the input
Q.17 Which of the following is a key parameter used to size the output capacitor in a rectifier circuit?
Input voltage
Desired ripple voltage
Load current
Switching frequency
Explanation - The capacitor value is chosen to achieve a specific ripple voltage for a given load current and input frequency.
Correct answer is: Desired ripple voltage
Q.18 What type of diode is typically used in a bridge rectifier to handle high voltage and high current?
Zener diode
Schottky diode
Silicon diode
Germanium diode
Explanation - Schottky diodes offer a low forward voltage drop and fast switching, making them ideal for high-power rectifiers.
Correct answer is: Schottky diode
Q.19 In a three-phase full-wave rectifier, how many diodes are typically used?
6
8
9
12
Explanation - A three-phase full-wave rectifier uses six diodes arranged to rectify each phase into DC.
Correct answer is: 6
Q.20 What is the purpose of an inductor in a DC-DC buck converter?
To smooth output voltage
To store energy during the switch off period
To regulate input voltage
To increase output current
Explanation - The inductor stores magnetic energy when the switch is on and releases it to maintain output current during off-time.
Correct answer is: To store energy during the switch off period
Q.21 Which of the following statements correctly describes a boost converter's output voltage relative to its input?
Always less than input voltage
Always equal to input voltage
Can be greater than input voltage
Cannot exceed input voltage by more than 10%
Explanation - A boost converter steps up the voltage; the output can be significantly higher than the input.
Correct answer is: Can be greater than input voltage
Q.22 In a PWM-controlled rectifier, what does PWM stand for?
Pulse Width Modulation
Power Wave Mode
Positive Wave Multiplication
Pulse Wave Measurement
Explanation - PWM refers to adjusting the duty cycle of a pulse to control power delivery.
Correct answer is: Pulse Width Modulation
Q.23 Which converter topology uses a transformer to provide electrical isolation between input and output?
Buck converter
Flyback converter
Boost converter
Forward converter
Explanation - Flyback converters employ a transformer for isolation and voltage conversion.
Correct answer is: Flyback converter
Q.24 In a half-controlled bridge rectifier, how many diodes and how many thyristors are used?
4 diodes and 2 thyristors
2 diodes and 4 thyristors
3 diodes and 3 thyristors
4 diodes and 4 thyristors
Explanation - A half-controlled bridge uses two diodes for positive half cycles and two thyristors for negative cycles.
Correct answer is: 4 diodes and 2 thyristors
Q.25 Which of the following is a typical application of a rectifier circuit?
Power supply for electronic devices
Motor speed control
Signal modulation
Voltage regulation for AC motors
Explanation - Rectifiers convert AC mains to DC used in power supplies for devices like computers and chargers.
Correct answer is: Power supply for electronic devices
Q.26 Which diode characteristic is most critical when selecting a diode for a high-frequency rectifier?
Forward voltage drop
Reverse recovery time
Maximum reverse voltage
Maximum forward current
Explanation - Short reverse recovery time minimizes loss at high switching frequencies.
Correct answer is: Reverse recovery time
Q.27 What is the main disadvantage of using a half-wave rectifier for a power supply?
High efficiency
Low output voltage ripple
High power dissipation in the diode
Complexity of the circuit
Explanation - Half-wave rectifiers use the diode for the entire AC cycle, leading to higher conduction losses.
Correct answer is: High power dissipation in the diode
Q.28 In a three-phase full-wave rectifier, what is the output ripple frequency if the line frequency is 60 Hz?
60 Hz
120 Hz
180 Hz
360 Hz
Explanation - The ripple frequency is three times the line frequency for a three-phase full-wave rectifier.
Correct answer is: 180 Hz
Q.29 Which converter type is best suited for providing isolated DC output from a DC input?
Buck converter
Boost converter
Flyback converter
Forward converter
Explanation - The flyback converter uses a transformer and provides electrical isolation between input and output.
Correct answer is: Flyback converter
Q.30 What does the term 'duty cycle' refer to in a PWM-controlled rectifier?
The ratio of output voltage to input voltage
The fraction of time the switch is ON during one period
The average current through the load
The ratio of ripple voltage to DC voltage
Explanation - Duty cycle is defined as the ON time divided by the total switching period.
Correct answer is: The fraction of time the switch is ON during one period
Q.31 Which of the following is NOT a function of a DC-DC converter?
Voltage regulation
Current regulation
Isolation
AC to DC conversion
Explanation - DC-DC converters convert DC voltage levels; AC-DC conversion is done by rectifiers.
Correct answer is: AC to DC conversion
Q.32 In a buck-boost converter, the output voltage can be expressed as Vout = Vinput × (D / (1-D)). Which variable represents the duty cycle?
Vinput
Vout
D
1-D
Explanation - D is the duty cycle, the fraction of the period the switch is ON.
Correct answer is: D
Q.33 What is the main role of a smoothing capacitor in a rectifier circuit?
To increase the ripple voltage
To reduce the ripple voltage
To block DC component
To increase the AC component
Explanation - A capacitor stores energy and releases it during voltage dips, smoothing the output.
Correct answer is: To reduce the ripple voltage
Q.34 Which of the following diodes has the lowest forward voltage drop?
Standard silicon diode
Schottky diode
Zener diode
LED
Explanation - Schottky diodes exhibit lower forward voltage drops (~0.2-0.3V) compared to silicon diodes (~0.7V).
Correct answer is: Schottky diode
Q.35 In a bridge rectifier, what is the voltage drop across the two diodes that are conducting at any given instant?
0 V
Half of the input voltage
The sum of the forward voltage drops of both diodes
The maximum of the two forward voltage drops
Explanation - Both diodes are forward biased; their voltage drops add up, typically ~1.4 V for silicon diodes.
Correct answer is: The sum of the forward voltage drops of both diodes
Q.36 What type of converter can step down voltage and also provide isolation?
Buck converter
Boost converter
Flyback converter
Forward converter
Explanation - The flyback converter uses a transformer to step down voltage and provide isolation.
Correct answer is: Flyback converter
Q.37 Which component in a buck converter primarily limits the ripple current in the output?
Inductor
Capacitor
Switch
Diode
Explanation - The inductor smooths the current, reducing ripple in the output.
Correct answer is: Inductor
Q.38 A full-wave rectifier using a center-tapped transformer requires how many diodes?
2
3
4
6
Explanation - The center-tapped transformer allows a two-diode configuration, one per half-cycle.
Correct answer is: 2
Q.39 Which of the following is a disadvantage of a boost converter?
It can only step up voltage
It has high conduction losses
It cannot handle high current
It requires a transformer for isolation
Explanation - A boost converter increases voltage but cannot step it down.
Correct answer is: It can only step up voltage
Q.40 What is the main function of a choke (inductor) in a DC-DC converter circuit?
To increase the ripple voltage
To store magnetic energy during switch operation
To block DC current
To rectify AC to DC
Explanation - The inductor stores energy when the switch is ON and releases it when the switch is OFF.
Correct answer is: To store magnetic energy during switch operation
Q.41 Which of the following is a key advantage of synchronous rectification over diode rectification?
Lower forward voltage drop
Higher conduction losses
Simpler design
Lower cost
Explanation - Synchronous rectifiers use MOSFETs with very low voltage drop, reducing power loss.
Correct answer is: Lower forward voltage drop
Q.42 What type of diode is commonly used in high-frequency rectifiers to minimize energy loss?
Schottky diode
Zener diode
Silicon diode
Germanium diode
Explanation - Schottky diodes have very low reverse recovery times, ideal for high-frequency applications.
Correct answer is: Schottky diode
Q.43 Which of the following statements about a full-wave rectifier is correct?
It uses only one diode.
It provides DC with twice the input frequency ripple.
It produces a negative output voltage.
It is unsuitable for high-power applications.
Explanation - Full-wave rectification uses both halves of the AC waveform, resulting in ripple at twice the AC frequency.
Correct answer is: It provides DC with twice the input frequency ripple.
Q.44 What is the primary purpose of an EMI filter in a rectifier circuit?
To increase ripple voltage
To reduce electromagnetic interference
To boost output voltage
To store charge
Explanation - EMI filters mitigate conducted and radiated noise generated by switching operations.
Correct answer is: To reduce electromagnetic interference
Q.45 In a half-bridge converter, which component is used to store energy during the OFF state of the switches?
Capacitor
Inductor
Resistor
Transformer
Explanation - The inductor retains energy during switching, providing smooth output.
Correct answer is: Inductor
Q.46 Which converter type uses a transformer and a diode bridge for isolation and rectification?
Flyback converter
Forward converter
Buck converter
Boost converter
Explanation - The flyback converter employs a transformer for isolation and a rectifier for DC output.
Correct answer is: Flyback converter
Q.47 In a full-wave center-tapped rectifier, if the primary voltage is 220 V RMS, what is the approximate peak voltage at the secondary (assuming no load)?
220 V
311 V
110 V
495 V
Explanation - Peak voltage = Vrms × √2 ≈ 220 × 1.414 = 311 V.
Correct answer is: 311 V
Q.48 Which of the following is a major benefit of using a DC-DC buck converter in a battery-powered system?
Increased power consumption
Reduced battery life
Higher efficiency
Lower output voltage
Explanation - Buck converters efficiently step down voltage, preserving battery life.
Correct answer is: Higher efficiency
Q.49 What is the relationship between ripple frequency and the number of phases in a multi-phase rectifier?
Ripple frequency is independent of phase number
Ripple frequency is equal to the number of phases times the line frequency
Ripple frequency decreases with more phases
Ripple frequency is always equal to the line frequency
Explanation - Multi-phase rectifiers produce ripple at n times the line frequency where n is the number of phases.
Correct answer is: Ripple frequency is equal to the number of phases times the line frequency
Q.50 Which of the following is a typical use case for a half-controlled bridge rectifier?
High-power AC motors
Low-voltage DC supplies with controlled output
Signal generation
AC-AC power conversion
Explanation - Half-controlled bridges allow control of the output voltage via thyristors while maintaining rectification.
Correct answer is: Low-voltage DC supplies with controlled output
Q.51 Which of the following best describes the operation of a PWM rectifier?
It uses a fixed duty cycle to rectify AC
It adjusts the duty cycle to control output voltage
It operates only at zero frequency
It is identical to a full-wave rectifier
Explanation - PWM rectifiers modulate the switching duty cycle to regulate DC output.
Correct answer is: It adjusts the duty cycle to control output voltage
Q.52 In a DC-DC converter, what is the function of the feedback loop?
To control the switch timing
To regulate the input voltage
To maintain a constant output voltage
To increase the ripple voltage
Explanation - The feedback loop senses output voltage and adjusts control signals to keep it constant.
Correct answer is: To maintain a constant output voltage
Q.53 Which of the following components is crucial for storing energy in a buck converter during the switch-off period?
Capacitor
Resistor
Inductor
Diode
Explanation - The inductor stores magnetic energy when the switch is ON and releases it during OFF time.
Correct answer is: Inductor
Q.54 What is the typical output ripple voltage in a well-filtered full-wave bridge rectifier with a large electrolytic capacitor?
Above 1 V
Between 500 mV and 1 V
Between 100 mV and 200 mV
Near 0 V
Explanation - A large electrolytic capacitor reduces ripple to a few hundred millivolts in a full-wave rectifier.
Correct answer is: Between 100 mV and 200 mV
Q.55 Which of the following is NOT a characteristic of a forward converter?
Uses a transformer for isolation
Can step-up or step-down voltage
Requires a freewheeling diode
Operates with a single-phase AC input
Explanation - Forward converters use DC input and a transformer for isolation; they do not directly use AC input.
Correct answer is: Operates with a single-phase AC input
Q.56 What is the main reason to use a diode bridge instead of a center-tapped transformer in a rectifier circuit?
Higher input voltage
Simpler construction
Higher ripple voltage
Lower efficiency
Explanation - A diode bridge eliminates the need for a center tap and reduces the number of transformer windings.
Correct answer is: Simpler construction
Q.57 Which of the following best describes a half-bridge DC-DC converter?
Two MOSFETs connected in series with a common source
Two MOSFETs connected in parallel with separate sources
Four MOSFETs forming a bridge configuration
A single MOSFET switching on and off
Explanation - The half-bridge uses two switches in series with a shared source to create a differential voltage.
Correct answer is: Two MOSFETs connected in series with a common source
Q.58 Which of the following is a common application of a flyback converter?
Powering AC motors directly
Providing isolated DC supply for embedded systems
Boosting RF signals
Regulating high voltage AC lines
Explanation - Flyback converters are widely used in low-power, isolated DC supplies for electronics.
Correct answer is: Providing isolated DC supply for embedded systems
Q.59 Which of the following diodes is most suitable for rectifying high-frequency signals in a DC-DC converter?
Standard silicon diode
Schottky diode
Zener diode
LED
Explanation - Schottky diodes have low reverse recovery times, making them ideal for high-frequency rectification.
Correct answer is: Schottky diode
Q.60 Which of the following statements best describes the principle of PWM control in power converters?
Increasing duty cycle increases output voltage
Duty cycle has no effect on output voltage
PWM only applies to rectifiers
PWM is used to reduce ripple voltage only
Explanation - Higher duty cycle allows more power to pass, raising the output voltage.
Correct answer is: Increasing duty cycle increases output voltage
Q.61 What is the primary function of the output filter in a DC-DC converter?
To regulate the output voltage
To smooth the output voltage and reduce ripple
To increase the output current
To block the input voltage
Explanation - The output filter (usually a capacitor) eliminates voltage spikes and smooths the DC output.
Correct answer is: To smooth the output voltage and reduce ripple
Q.62 Which type of converter can provide both isolation and step-down voltage conversion without a transformer?
Buck converter
Boost converter
Flyback converter
Forward converter
Explanation - The flyback converter uses a transformer for isolation and steps down voltage.
Correct answer is: Flyback converter
Q.63 Which of the following is a characteristic of a half-wave rectifier's output waveform?
Continuous DC
Alternating DC with zero crossings
Pulsating DC with positive half-cycles only
Negative DC with no ripple
Explanation - A half-wave rectifier only allows the positive half-cycles to pass, resulting in pulsating DC.
Correct answer is: Pulsating DC with positive half-cycles only
Q.64 In a buck converter, what is the relationship between output voltage (Vout) and input voltage (Vin) and duty cycle (D)?
Vout = Vin / D
Vout = Vin × D
Vout = Vin × (1 - D)
Vout = Vin / (1 - D)
Explanation - The ideal buck converter output is Vin times the duty cycle.
Correct answer is: Vout = Vin × D
Q.65 Which of the following diodes would be most suitable for use in a high-power rectifier due to its high current rating?
1N4001
1N4148
1N5819
1N4007
Explanation - 1N4007 can handle up to 1 A and high voltage, making it suitable for power rectifiers.
Correct answer is: 1N4007
Q.66 What is the effect of adding a larger smoothing capacitor in a rectifier circuit?
Increases ripple voltage
Decreases ripple voltage
Has no effect on ripple voltage
Increases AC voltage
Explanation - A larger capacitor stores more charge, smoothing out voltage dips and reducing ripple.
Correct answer is: Decreases ripple voltage
Q.67 Which component is commonly used to rectify high-frequency AC signals in a DC-DC converter?
Rectangular diode
Schottky diode
Zener diode
LED
Explanation - Schottky diodes have a low forward voltage drop and fast switching, ideal for high-frequency rectification.
Correct answer is: Schottky diode
Q.68 Which of the following describes a 'zero-crossing' trigger in a controlled rectifier?
The switch fires when voltage is at its maximum
The switch fires when voltage crosses zero
The switch fires at a constant interval
The switch does not fire at all
Explanation - Zero-crossing triggering aligns the switch conduction with the zero-crossing of the AC waveform, reducing EMI.
Correct answer is: The switch fires when voltage crosses zero
Q.69 In a DC-DC boost converter, when the duty cycle is increased, what happens to the output voltage?
It decreases
It remains the same
It increases
It becomes zero
Explanation - A higher duty cycle allows more energy to be stored in the inductor, raising the output voltage.
Correct answer is: It increases
Q.70 What is the primary function of the freewheeling diode in a buck converter?
To block reverse current
To provide a path for inductor current during switch OFF
To increase output voltage
To regulate input voltage
Explanation - The freewheeling diode allows the inductor current to continue flowing when the switch turns off.
Correct answer is: To provide a path for inductor current during switch OFF
Q.71 Which of the following is a typical application of a half-wave rectifier?
Powering a 12 V LED
Providing a DC supply for a microcontroller
Generating high-power AC
Smoothing a high-current DC supply
Explanation - Half-wave rectifiers are simple and can supply low-power DC such as for a single LED.
Correct answer is: Powering a 12 V LED
Q.72 Which of the following describes the operation of a half-controlled bridge rectifier?
All diodes are conducting
All thyristors are conducting
Some diodes and thyristors are conducting simultaneously
Only one component is active at a time
Explanation - A half-controlled bridge uses diodes for one polarity and thyristors for the other.
Correct answer is: Some diodes and thyristors are conducting simultaneously
Q.73 What is the typical duty cycle range for a buck converter operating in continuous conduction mode?
0-10%
10-90%
70-100%
100%
Explanation - In continuous mode, duty cycle typically varies between 10% and 90% for stable operation.
Correct answer is: 10-90%
Q.74 Which of the following statements about a forward converter is correct?
It uses a transformer for isolation
It cannot provide isolation
It uses only diodes and a transformer
It is identical to a buck converter
Explanation - Forward converters use a transformer to provide isolation between input and output.
Correct answer is: It uses a transformer for isolation
Q.75 What is the effect of increasing the switching frequency in a rectifier circuit?
Increases ripple voltage
Decreases ripple voltage
Has no effect on ripple voltage
Increases DC output voltage
Explanation - Higher switching frequency reduces the time for voltage to sag between pulses, reducing ripple.
Correct answer is: Decreases ripple voltage
Q.76 Which of the following components is used to limit the peak voltage in a flyback converter?
Resistor
Capacitor
Snubber circuit
Diode
Explanation - Snubber circuits absorb voltage spikes to protect components in flyback converters.
Correct answer is: Snubber circuit
Q.77 What does the term 'continuous conduction mode' refer to in a buck converter?
The switch is always ON
The output capacitor is always charged
The inductor current never falls to zero
The output voltage is continuous
Explanation - In continuous mode, the inductor current remains above zero throughout the cycle.
Correct answer is: The inductor current never falls to zero
Q.78 Which of the following is a main advantage of using a bridge rectifier over a center-tapped rectifier?
Lower output voltage
Fewer components required
Higher ripple voltage
Increased complexity
Explanation - A bridge rectifier uses four diodes and no center-tapped transformer, simplifying construction.
Correct answer is: Fewer components required
Q.79 Which of the following is a typical use for a PWM rectifier in power electronics?
Direct AC-DC conversion
Voltage regulation in a DC-DC converter
Providing isolation between circuits
Generating AC waveforms
Explanation - PWM rectifiers adjust duty cycles to regulate DC output voltage in converters.
Correct answer is: Voltage regulation in a DC-DC converter
Q.80 Which component in a rectifier is responsible for preventing reverse current flow during the negative half-cycle?
Capacitor
Resistor
Diode
Inductor
Explanation - The diode blocks reverse current, allowing only forward conduction.
Correct answer is: Diode
Q.81 What is the effect of using a transformer with a higher turns ratio in a rectifier circuit?
Lower output voltage
Higher output voltage
Lower ripple frequency
Higher ripple frequency
Explanation - A higher turns ratio steps up the secondary voltage, increasing the rectified DC voltage.
Correct answer is: Higher output voltage
Q.82 Which of the following statements about a synchronous buck converter is true?
It uses a diode in the freewheeling path
It uses a MOSFET with a low forward voltage drop
It has higher conduction losses than diode-based buck converters
It cannot be controlled by PWM
Explanation - Synchronous buck converters replace the freewheeling diode with a MOSFET to reduce conduction losses.
Correct answer is: It uses a MOSFET with a low forward voltage drop
Q.83 In a boost converter, which component is primarily responsible for storing energy during the switch ON period?
Capacitor
Inductor
Resistor
Diode
Explanation - The inductor stores magnetic energy during ON time and releases it to increase output voltage.
Correct answer is: Inductor
Q.84 Which of the following is a characteristic of a half-wave rectifier output?
Smooth DC with low ripple
High ripple with positive pulses only
Zero output voltage
Negative DC output
Explanation - Half-wave rectifiers produce pulsating DC with high ripple because only one half-cycle passes.
Correct answer is: High ripple with positive pulses only
Q.85 Which of the following is the primary function of a diode in a bridge rectifier?
To store energy
To block reverse voltage and conduct forward voltage
To regulate current
To increase ripple
Explanation - Diodes allow current in one direction and block it in the opposite direction, enabling rectification.
Correct answer is: To block reverse voltage and conduct forward voltage
Q.86 What is the effect of adding a snubber circuit across a flyback transformer?
Increases the output voltage
Reduces voltage spikes and protects the diode
Increases ripple voltage
Decreases the switching frequency
Explanation - Snubber circuits absorb voltage transients, protecting components from high-voltage spikes.
Correct answer is: Reduces voltage spikes and protects the diode
Q.87 Which of the following topologies is commonly used for high-efficiency DC-DC conversion in power supplies?
Buck converter
Boost converter
Flyback converter
All of the above
Explanation - All listed topologies can achieve high efficiency when designed appropriately.
Correct answer is: All of the above
Q.88 Which of the following components is responsible for providing isolation between input and output in a flyback converter?
Inductor
Capacitor
Transformer
Diode
Explanation - The transformer provides galvanic isolation between the input and output circuits.
Correct answer is: Transformer
Q.89 What is the typical ripple voltage in a well-designed full-wave bridge rectifier with a properly sized filter capacitor?
0.1 V
1 V
10 V
100 V
Explanation - A properly sized capacitor can reduce ripple voltage to around 0.1 V or less.
Correct answer is: 0.1 V
Q.90 Which of the following diodes has the lowest forward voltage drop among typical silicon diodes?
1N4001
1N4148
1N5819
1N4007
Explanation - The 1N5819 is a Schottky diode with a forward drop typically around 0.2–0.3 V.
Correct answer is: 1N5819
Q.91 Which of the following is a major disadvantage of a half-wave rectifier?
Very high efficiency
High ripple voltage
Complex circuit design
Low output voltage
Explanation - Because only half the AC waveform is used, the ripple is substantial compared to full-wave rectification.
Correct answer is: High ripple voltage
Q.92 In a DC-DC buck converter, which component is responsible for releasing stored energy back to the output when the switch turns off?
Capacitor
Inductor
Diode
Transformer
Explanation - The inductor releases its stored energy through the diode into the output when the switch opens.
Correct answer is: Inductor
Q.93 Which of the following is a key advantage of using PWM control in a rectifier?
Lower conduction losses
Higher ripple factor
Simpler control circuitry
Increased switching frequency
Explanation - PWM allows precise control over power delivery, reducing losses by adjusting duty cycle.
Correct answer is: Lower conduction losses
Q.94 Which of the following statements about a half-bridge converter is correct?
It uses four MOSFETs in a bridge configuration
It requires a transformer for isolation
It uses two MOSFETs in series with a shared source
It cannot provide isolated output
Explanation - The half-bridge configuration uses two switches in series with a common source to produce differential voltage.
Correct answer is: It uses two MOSFETs in series with a shared source
Q.95 In a half-wave bridge rectifier, how many diodes are used?
2
4
6
8
Explanation - A half-wave bridge rectifier requires four diodes arranged to conduct during each half-cycle.
Correct answer is: 4
Q.96 What is the purpose of a freewheeling diode in a DC-DC converter?
To limit current
To provide a path for inductive current during switch OFF
To increase output voltage
To reduce ripple voltage
Explanation - The freewheeling diode allows current to continue flowing through the inductor when the main switch turns off.
Correct answer is: To provide a path for inductive current during switch OFF
Q.97 Which of the following is a typical application of a boost converter?
Powering a high-voltage AC motor
Step-down voltage in a solar charger
Providing isolated DC to a microcontroller
Increasing DC voltage from a battery to power a load
Explanation - A boost converter raises the output voltage above the input, suitable for low-voltage sources.
Correct answer is: Increasing DC voltage from a battery to power a load
Q.98 Which of the following is NOT a typical component of a PWM-controlled rectifier?
Switching transistor
Control logic
Rectifying diode
Transformer core
Explanation - PWM-controlled rectifiers generally use diodes and transistors; a transformer core is not needed.
Correct answer is: Transformer core
Q.99 What is the function of a voltage regulator in a DC-DC converter circuit?
To increase the output voltage
To maintain a constant output voltage regardless of load changes
To store energy in the inductor
To filter ripple voltage
Explanation - A voltage regulator uses feedback to adjust the control signals, keeping Vout stable.
Correct answer is: To maintain a constant output voltage regardless of load changes
Q.100 In a flyback converter, what is the purpose of the primary winding?
To provide isolation
To store magnetic energy during switching
To rectify AC to DC
To filter ripple voltage
Explanation - The primary winding stores energy in its magnetic core while the switch is on.
Correct answer is: To store magnetic energy during switching
Q.101 Which of the following is a typical use for a full-wave bridge rectifier?
Powering low-power DC circuits from AC mains
Generating high-frequency AC signals
Providing isolation between circuits
Sensing AC voltage levels
Explanation - Full-wave bridge rectifiers convert AC mains to DC for many electronic devices.
Correct answer is: Powering low-power DC circuits from AC mains
Q.102 What is the primary advantage of using a synchronous rectifier in a buck converter?
Simpler design
Higher efficiency due to lower conduction loss
Increased ripple voltage
Lower component count
Explanation - Synchronous rectifiers use MOSFETs with low on-resistance, reducing power dissipation.
Correct answer is: Higher efficiency due to lower conduction loss
Q.103 Which of the following best describes the operation of a buck converter?
It steps up voltage
It steps down voltage
It isolates input and output
It converts AC to DC
Explanation - A buck converter reduces the input voltage to a lower output voltage.
Correct answer is: It steps down voltage
Q.104 Which of the following diodes is commonly used in rectifier circuits due to its high current rating?
1N4148
1N4007
1N5819
1N4001
Explanation - 1N4007 is rated for up to 1 A and is widely used in power rectification.
Correct answer is: 1N4007
Q.105 Which of the following is a common disadvantage of a flyback converter?
High switching frequency
Complex control scheme
Limited isolation capability
Large output voltage ripple
Explanation - Flyback converters often produce larger ripple due to the transformer’s energy transfer dynamics.
Correct answer is: Large output voltage ripple
Q.106 Which of the following best describes a half-wave rectifier's output waveform?
Smooth DC
Pulsating DC with positive half cycles only
Negative DC
Zero voltage
Explanation - Only the positive half of the AC waveform passes through a half-wave rectifier.
Correct answer is: Pulsating DC with positive half cycles only
Q.107 In a full-wave bridge rectifier, the DC output voltage is typically ________ of the peak AC voltage.
Equal to
Greater than
Half of
Zero
Explanation - The DC output is approximately 0.9 times the peak AC voltage after accounting for diode drops.
Correct answer is: Greater than
Q.108 Which of the following is a typical component used to limit the peak reverse voltage in a rectifier circuit?
Resistor
Inductor
Capacitor
Zener diode
Explanation - A Zener diode can clamp the reverse voltage across the diode during off periods.
Correct answer is: Zener diode
Q.109 Which of the following is a characteristic of a PWM-controlled buck converter?
Constant output voltage regardless of load
Variable output voltage controlled by duty cycle
No need for feedback
Uses only diodes for switching
Explanation - PWM control adjusts duty cycle to regulate the output voltage in a buck converter.
Correct answer is: Variable output voltage controlled by duty cycle
Q.110 In a DC-DC converter, the output capacitor primarily serves what function?
To store energy
To filter ripple voltage
To increase output voltage
To block AC components
Explanation - The output capacitor smooths the DC voltage, reducing ripple.
Correct answer is: To filter ripple voltage
Q.111 What is the primary disadvantage of a half-controlled bridge rectifier compared to a fully controlled bridge?
Requires fewer control signals
Higher conduction losses
Lower output voltage
More complex circuitry
Explanation - Half-controlled bridges use diodes for one polarity, which have higher forward voltage drops than controlled thyristors.
Correct answer is: Higher conduction losses
Q.112 Which of the following statements about a three-phase rectifier is true?
It produces a DC output with higher ripple than a single-phase rectifier
It can be used with a center-tapped transformer
It requires six diodes in a full-bridge configuration
It is not suitable for power applications
Explanation - A three-phase full-bridge rectifier uses six diodes to rectify each phase.
Correct answer is: It requires six diodes in a full-bridge configuration
Q.113 Which of the following is a typical application for a flyback converter?
Powering a laptop charger
Step-down regulation for LED drivers
Providing isolated power for a microcontroller
Generating high-voltage AC
Explanation - Flyback converters provide isolated DC output from a low-voltage source for embedded devices.
Correct answer is: Providing isolated power for a microcontroller
Q.114 In a PWM rectifier, what does adjusting the duty cycle achieve?
Changing the output voltage
Changing the input frequency
Changing the ripple frequency
Changing the diode type
Explanation - The duty cycle determines the average voltage delivered to the load.
Correct answer is: Changing the output voltage
Q.115 Which of the following is a typical parameter used to evaluate the efficiency of a buck converter?
Output voltage ripple
Input voltage
Switching frequency
Power efficiency
Explanation - Efficiency is calculated as output power divided by input power, indicating losses.
Correct answer is: Power efficiency
Q.116 What is the function of the transformer in a flyback converter?
To step-up or step-down voltage and provide isolation
To filter output voltage
To regulate input current
To store energy in the output capacitor
Explanation - The flyback transformer transfers energy between primary and secondary and isolates input from output.
Correct answer is: To step-up or step-down voltage and provide isolation
Q.117 Which of the following best describes the operation of a half-bridge DC-DC converter?
It uses two MOSFETs in series to create a differential voltage
It uses four MOSFETs in a full-bridge configuration
It uses a transformer for isolation
It cannot provide regulated output
Explanation - The half-bridge configuration uses two switches in series with a common source to produce a varying voltage.
Correct answer is: It uses two MOSFETs in series to create a differential voltage
Q.118 Which of the following is a typical output of a half-wave bridge rectifier?
Smooth DC
High ripple DC
Zero voltage
Negative DC
Explanation - A half-wave bridge rectifier only allows half of the AC waveform, resulting in high ripple.
Correct answer is: High ripple DC
Q.119 Which of the following is true about a synchronous buck converter?
It uses a diode instead of a MOSFET for the freewheeling path
It has higher conduction losses than diode-based buck converters
It replaces the freewheeling diode with a MOSFET to reduce losses
It cannot be controlled by PWM
Explanation - Synchronous buck converters use MOSFETs in the freewheeling path to lower conduction losses.
Correct answer is: It replaces the freewheeling diode with a MOSFET to reduce losses
Q.120 What is the main function of a diode bridge in a rectifier circuit?
To filter out noise
To allow current flow in one direction only
To store energy in the transformer
To control the switching frequency
Explanation - Diodes in a bridge rectifier permit current to flow only during the appropriate half-cycle, producing DC.
Correct answer is: To allow current flow in one direction only
Q.121 Which of the following topologies is best suited for providing a regulated isolated DC output from a low-voltage DC source?
Buck converter
Flyback converter
Boost converter
Forward converter
Explanation - Flyback converters are ideal for low-power isolated DC outputs.
Correct answer is: Flyback converter
Q.122 In a buck-boost converter, if the duty cycle increases, what happens to the output voltage?
It increases
It decreases
It stays the same
It becomes zero
Explanation - Increasing the duty cycle allows more energy to be transferred, raising the output voltage.
Correct answer is: It increases
Q.123 Which of the following components is typically used as a freewheeling path in a buck converter?
Inductor
Capacitor
Diode
Transistor
Explanation - The freewheeling diode provides a path for the inductor current when the main switch is off.
Correct answer is: Diode
Q.124 What is the typical ripple voltage in a well-filtered full-wave bridge rectifier with a 100 µF capacitor at a load of 1 A?
1 V
50 mV
10 V
0.1 mV
Explanation - A 100 µF capacitor can reduce ripple to tens of millivolts at moderate loads.
Correct answer is: 50 mV
Q.125 Which of the following statements about a half-wave rectifier is true?
It uses four diodes
It uses a transformer with a center tap
It only allows positive half cycles
It produces no ripple
Explanation - A half-wave rectifier conducts only during the positive half of the AC waveform.
Correct answer is: It only allows positive half cycles
Q.126 Which of the following best describes a full-wave bridge rectifier?
It uses a single diode to rectify AC
It uses two diodes to rectify both halves of AC
It uses four diodes to rectify AC with no center tap
It uses a transformer with no diodes
Explanation - A full-wave bridge rectifier requires four diodes and no center-tapped transformer.
Correct answer is: It uses four diodes to rectify AC with no center tap
Q.127 Which of the following components is commonly used to store energy in a buck converter during the switch ON period?
Capacitor
Inductor
Resistor
Diode
Explanation - The inductor stores energy while the switch conducts and releases it when the switch is off.
Correct answer is: Inductor
Q.128 What is the main advantage of using a synchronous rectifier in a DC-DC converter?
Lower conduction losses
Higher ripple voltage
Simpler control circuit
Lower cost
Explanation - Synchronous rectifiers replace diodes with MOSFETs, reducing voltage drop and power loss.
Correct answer is: Lower conduction losses
Q.129 Which of the following is a typical characteristic of a boost converter?
It steps down voltage
It steps up voltage
It provides isolation
It is only used in AC applications
Explanation - A boost converter increases the input DC voltage to a higher output voltage.
Correct answer is: It steps up voltage
Q.130 In a rectifier circuit, which component is responsible for blocking reverse current during the negative half cycle?
Capacitor
Resistor
Inductor
Diode
Explanation - The diode allows current only in the forward direction, blocking reverse current.
Correct answer is: Diode
Q.131 Which of the following statements about a flyback converter is true?
It cannot provide isolation
It uses a transformer for isolation and energy storage
It operates at low switching frequencies
It uses only a diode for rectification
Explanation - The flyback converter’s transformer stores energy during the switch ON period and transfers it during OFF.
Correct answer is: It uses a transformer for isolation and energy storage
Q.132 Which of the following components is most commonly used to limit current in a rectifier circuit?
Resistor
Capacitor
Inductor
Diode
Explanation - A resistor limits the current flowing through the rectifier, protecting components.
Correct answer is: Resistor
Q.133 What is the role of the freewheeling diode in a buck converter?
To block reverse voltage
To provide a path for inductor current during switch OFF
To step up the output voltage
To reduce ripple voltage
Explanation - The freewheeling diode allows the inductor current to flow when the main switch is off.
Correct answer is: To provide a path for inductor current during switch OFF
Q.134 Which of the following is a key advantage of using a PWM controller in a rectifier circuit?
Higher conduction losses
Lower ripple voltage
Simpler design
Higher switching frequency
Explanation - PWM can control the duty cycle to smooth the output voltage, reducing ripple.
Correct answer is: Lower ripple voltage
Q.135 Which of the following is a typical application for a full-wave bridge rectifier?
Generating AC signals
Powering a low-power DC load
Providing isolation between circuits
Generating high-frequency AC
Explanation - Full-wave bridge rectifiers convert AC mains to DC for many electronic devices.
Correct answer is: Powering a low-power DC load
Q.136 In a DC-DC converter, the duty cycle determines what aspect of the output?
Ripple voltage
Load current
Average output voltage
Input voltage
Explanation - The duty cycle directly controls the average output voltage in a switching converter.
Correct answer is: Average output voltage
Q.137 Which of the following statements about a half-wave bridge rectifier is correct?
It uses only two diodes
It uses four diodes
It requires a transformer with a center tap
It is identical to a full-wave bridge rectifier
Explanation - A half-wave bridge rectifier also uses four diodes arranged to allow conduction in each half-cycle.
Correct answer is: It uses four diodes
Q.138 Which of the following topologies is commonly used to provide a regulated isolated DC output from a mains AC source?
Buck converter
Boost converter
Flyback converter
Forward converter
Explanation - Flyback converters are used for isolated DC supplies in power adapters.
Correct answer is: Flyback converter
Q.139 Which of the following is a typical application of a buck converter?
Powering a high-voltage AC motor
Stepping up voltage
Stepping down voltage for battery charging
Providing isolated DC output
Explanation - A buck converter reduces voltage and is used for charging batteries from a higher voltage source.
Correct answer is: Stepping down voltage for battery charging
Q.140 Which of the following is a common disadvantage of a half-wave rectifier?
Higher efficiency
Lower ripple
Higher output voltage
Limited use at high power
Explanation - Half-wave rectifiers are inefficient at high power due to the unused half-cycle.
Correct answer is: Limited use at high power
Q.141 In a PWM rectifier, increasing the duty cycle generally has what effect on the output voltage?
Decreases it
Increases it
Keeps it constant
Makes it zero
Explanation - A higher duty cycle delivers more average power, raising the output voltage.
Correct answer is: Increases it
Q.142 Which of the following best describes the operation of a full-wave bridge rectifier?
It uses a single diode to rectify AC
It uses two diodes for half-wave rectification
It uses four diodes to rectify both halves of AC
It uses a transformer with a center tap
Explanation - Four diodes are arranged to conduct alternately on each half-cycle, producing DC.
Correct answer is: It uses four diodes to rectify both halves of AC
Q.143 Which of the following is a typical application of a half-controlled bridge rectifier?
Powering a small DC device from AC
Providing isolated DC for a microcontroller
Generating high-voltage AC
Step-down regulation for LED drivers
Explanation - A half-controlled bridge rectifier can be used to supply low-power DC devices from AC mains.
Correct answer is: Powering a small DC device from AC
Q.144 In a DC-DC buck converter, what component is responsible for converting the inductor current into DC voltage when the main switch is off?
Capacitor
Inductor
Diode
Transformer
Explanation - The diode provides a path for the inductor current when the switch is OFF, maintaining output current.
Correct answer is: Diode
Q.145 Which of the following components is commonly used to store energy in a buck converter?
Resistor
Capacitor
Inductor
Diode
Explanation - The inductor stores magnetic energy during conduction and releases it during OFF periods.
Correct answer is: Inductor
Q.146 Which of the following describes the output of a half-wave rectifier?
Smooth DC
Pulsating DC with positive half cycles only
Negative DC
Zero voltage
Explanation - A half-wave rectifier allows only the positive half of the AC waveform, resulting in high ripple.
Correct answer is: Pulsating DC with positive half cycles only
Q.147 In a PWM-controlled rectifier, what is the typical role of the duty cycle?
To control the input voltage
To adjust the output voltage
To regulate the ripple frequency
To determine the transformer turns ratio
Explanation - The duty cycle controls the average power delivered to the load, thus adjusting the output voltage.
Correct answer is: To adjust the output voltage
Q.148 Which of the following components is most critical for protecting a rectifier from reverse voltage spikes?
Resistor
Zener diode
Inductor
Capacitor
Explanation - A Zener diode clamps the reverse voltage, protecting the rectifier diodes.
Correct answer is: Zener diode
Q.149 Which of the following is a typical component of a half-wave bridge rectifier?
Two diodes
Four diodes
Six diodes
Eight diodes
Explanation - A half-wave bridge rectifier also uses four diodes to conduct on each half-cycle.
Correct answer is: Four diodes
Q.150 What is the main advantage of using a full-wave bridge rectifier over a half-wave rectifier?
Higher ripple voltage
Higher output voltage
Higher efficiency
Simpler circuitry
Explanation - Full-wave rectifiers use both halves of the AC waveform, providing more efficient conversion.
Correct answer is: Higher efficiency
Q.151 Which of the following topologies is best suited for providing an isolated DC supply from AC mains?
Buck converter
Flyback converter
Boost converter
Forward converter
Explanation - Flyback converters use a transformer to isolate the output from the mains input.
Correct answer is: Flyback converter
Q.152 In a DC-DC buck converter, the output capacitor serves primarily to ________.
Store energy
Reduce ripple voltage
Step down voltage
Increase output current
Explanation - The output capacitor filters the ripple in the output DC voltage.
Correct answer is: Reduce ripple voltage
Q.153 Which of the following statements about a flyback converter is correct?
It uses a transformer for isolation and energy storage
It cannot provide isolated output
It operates only with AC input
It is used only for high-power applications
Explanation - The flyback transformer stores energy and provides isolation between primary and secondary.
Correct answer is: It uses a transformer for isolation and energy storage