Q.1 Which symbol in a circuit diagram represents a diode?
⚙️
➡️
⊕
➔
Explanation - The diode symbol is a triangle pointing to a line; the arrow points to the cathode.
Correct answer is: ➡️
Q.2 What is the typical forward voltage drop of a silicon diode?
0.2 V
0.7 V
1.5 V
2.7 V
Explanation - A silicon diode usually drops about 0.7 V when forward‑biased.
Correct answer is: 0.7 V
Q.3 Which device emits light when current passes through it?
Zener diode
LED
SCR
IGBT
Explanation - An LED (Light Emitting Diode) produces light under forward bias.
Correct answer is: LED
Q.4 What is a simple half‑wave rectifier made of?
Two diodes
One diode
Three transistors
An inverter
Explanation - A half‑wave rectifier uses a single diode to allow only one half of the AC cycle.
Correct answer is: One diode
Q.5 Which component blocks current flow in only one direction?
Transistor
Resistor
Capacitor
Diode
Explanation - A diode conducts only in the forward direction and blocks reverse current.
Correct answer is: Diode
Q.6 Which terminal of a diode is the cathode?
The end with the arrow
The end without the arrow
The middle of the triangle
The side with a line
Explanation - In the diode symbol the arrow points to the cathode; the line is the cathode terminal.
Correct answer is: The end without the arrow
Q.7 Why are diodes used in power supply circuits?
To store energy
To filter noise
To convert AC to DC
To increase voltage
Explanation - Diodes allow current to flow in one direction, turning alternating current into direct current.
Correct answer is: To convert AC to DC
Q.8 What is the main purpose of a Zener diode?
To limit current
To regulate voltage
To amplify signals
To store charge
Explanation - A Zener diode conducts in reverse bias to keep voltage at a fixed level.
Correct answer is: To regulate voltage
Q.9 In reverse bias, what happens to a diode if the voltage exceeds its rating?
It starts conducting forward
Its resistance drops to zero
It may break down and conduct reverse current
Nothing; it stays off
Explanation - Exceeding the reverse breakdown voltage can cause a diode to conduct in reverse and possibly get damaged.
Correct answer is: It may break down and conduct reverse current
Q.10 A small signal diode typically can handle currents up to:
1 mA
10 mA
100 mA
1 A
Explanation - Small signal diodes are rated for currents usually up to about 10 mA.
Correct answer is: 10 mA
Q.11 What is the function of a full‑wave bridge rectifier?
To convert DC to AC
To smooth out voltage ripple
To allow both halves of AC to become DC
To increase the voltage level
Explanation - A bridge rectifier uses four diodes to rectify the entire AC waveform into DC.
Correct answer is: To allow both halves of AC to become DC
Q.12 Which parameter is NOT typically used to specify a power diode?
Peak inverse voltage (PIV)
Forward current (If)
Gate threshold voltage (Vgs(th))
Maximum junction temperature (Tj,max)
Explanation - Gate threshold voltage applies to MOSFETs, not diodes.
Correct answer is: Gate threshold voltage (Vgs(th))
Q.13 A diode with a peak inverse voltage of 400 V is suitable for which of the following?
Low‑voltage LED applications
High‑voltage rectifiers in power supplies
Signal processing circuits
Audio amplifiers
Explanation - 400 V PIV diodes are used where high reverse voltages are expected, such as in power supply rectifiers.
Correct answer is: High‑voltage rectifiers in power supplies
Q.14 Which of the following devices is used for high‑speed switching in power electronics?
Silicon Controlled Rectifier (SCR)
Triode
MOSFET
Vacuum tube
Explanation - MOSFETs can turn on and off very rapidly, making them ideal for high‑speed switching.
Correct answer is: MOSFET
Q.15 What does 'Rds(on)' represent in a MOSFET?
Resistance when the device is on
Drain‑source voltage
Gate threshold voltage
Reverse recovery time
Explanation - Rds(on) is the on‑resistance between drain and source when the MOSFET is fully enhanced.
Correct answer is: Resistance when the device is on
Q.16 An IGBT combines features of which two device types?
MOSFET and BJT
Diode and BJT
SCR and TRIAC
MOSFET and diode
Explanation - IGBTs use a MOSFET gate for fast switching and a BJT for current handling.
Correct answer is: MOSFET and BJT
Q.17 Which of these parameters is most critical for selecting a MOSFET in a switching power supply?
Gate threshold voltage
Maximum junction temperature
On‑resistance (Rds(on))
Package type
Explanation - Lower Rds(on) reduces conduction losses, which is essential in power applications.
Correct answer is: On‑resistance (Rds(on))
Q.18 What is reverse recovery time (trr) in a diode?
Time for the diode to recover from forward bias to reverse blocking
Time to recharge the diode's capacitance
Time for the diode to cool down
Time it takes for the diode to reach forward voltage
Explanation - trr is the interval during which the diode still conducts after the applied voltage changes direction.
Correct answer is: Time for the diode to recover from forward bias to reverse blocking
Q.19 Which type of diode is best suited for high‑frequency rectification?
Fast‑recovery diode
Zener diode
Light emitting diode
Standard silicon diode
Explanation - Fast‑recovery diodes switch off quickly, reducing switching losses at high frequencies.
Correct answer is: Fast‑recovery diode
Q.20 Which of these devices can be used as a bidirectional switch in a DC‑DC converter?
SCR
MOSFET
IGBT
Triac
Explanation - A Triac conducts in both directions when triggered, making it suitable for bidirectional control.
Correct answer is: Triac
Q.21 What does 'Vds' stand for in a MOSFET specification?
Drain‑source voltage
Gate‑source voltage
Drain‑source current
Voltage drop across the source
Explanation - Vds is the maximum voltage that can be applied between drain and source without breaking down.
Correct answer is: Drain‑source voltage
Q.22 In a power MOSFET, which parameter indicates how quickly it can be turned off?
Rds(on)
Gate charge (Qg)
Drain‑source voltage
Reverse recovery time
Explanation - A smaller gate charge means less energy is needed to change the gate voltage, allowing faster switching.
Correct answer is: Gate charge (Qg)
Q.23 Which device is most suitable for use as a high‑current, low‑drop switch in motor drivers?
IGBT
MOSFET
SCR
Zener diode
Explanation - MOSFETs provide low on‑resistance and can handle high currents with fast switching.
Correct answer is: MOSFET
Q.24 What is the typical application of an SCR in power electronics?
Voltage regulation
High‑speed switching
Controlled rectification
Signal amplification
Explanation - SCRs are used for controlled rectification where a gate signal initiates conduction.
Correct answer is: Controlled rectification
Q.25 A power diode rated for 1 kV peak inverse voltage and 2 A forward current is best used for:
Low‑voltage LED circuits
High‑voltage power supply rectifiers
Audio amplifier feedback
Signal line termination
Explanation - Such a diode can withstand high reverse voltages and handle moderate current levels typical in power supplies.
Correct answer is: High‑voltage power supply rectifiers
Q.26 Which parameter defines how much current a MOSFET can safely handle in continuous operation?
Drain current (Id)
Gate threshold voltage (Vgs(th))
Gate charge (Qg)
Reverse recovery time (trr)
Explanation - Id specifies the maximum continuous current the MOSFET can carry without overheating.
Correct answer is: Drain current (Id)
Q.27 Which device has a built‑in latch‑up protection feature?
IGBT
SCR
Diode
MOSFET
Explanation - IGBTs often include latch‑up protection to prevent permanent damage when over‑stress occurs.
Correct answer is: IGBT
Q.28 Which of the following is a major advantage of using a Schottky diode in rectifiers?
High reverse voltage rating
Low forward voltage drop
Fast reverse recovery
High current capability
Explanation - Schottky diodes have a much lower forward voltage drop, reducing conduction losses.
Correct answer is: Low forward voltage drop
Q.29 Which parameter is most important for a diode used in high‑frequency applications?
Peak inverse voltage (PIV)
Reverse recovery time (trr)
Forward current rating
Package type
Explanation - Shorter trr reduces switching losses at high frequencies.
Correct answer is: Reverse recovery time (trr)
Q.30 What does the term 'latch‑up' refer to in power MOSFETs?
An increase in on‑resistance
A sudden drop in voltage
A condition where the device conducts indefinitely
A protective shutdown mode
Explanation - Latch‑up is a failure mode where the MOSFET remains on even after the gate is removed.
Correct answer is: A condition where the device conducts indefinitely
Q.31 Which device is typically used as the main switch in a DC‑DC buck converter?
IGBT
MOSFET
SCR
Triac
Explanation - MOSFETs are chosen for their low conduction losses and fast switching in buck converters.
Correct answer is: MOSFET
Q.32 When selecting a MOSFET for a 12 V, 10 A buck converter, which specification should be prioritized?
Gate threshold voltage
Drain‑source voltage
On‑resistance (Rds(on))
Package thermal resistance
Explanation - Lower Rds(on) reduces conduction losses at 10 A, improving efficiency.
Correct answer is: On‑resistance (Rds(on))
Q.33 What is the main source of switching loss in a MOSFET?
On‑resistance heating
Gate drive energy
Reverse recovery current
Leakage current
Explanation - Switching loss is mainly due to the energy required to charge and discharge the gate capacitance.
Correct answer is: Gate drive energy
Q.34 Which parameter describes the maximum temperature a semiconductor junction can reach before failure?
Tj,max
Toff
Vds
Id
Explanation - Tj,max is the maximum junction temperature specified for reliable operation.
Correct answer is: Tj,max
Q.35 A device that conducts current only after its gate voltage reaches a certain threshold is called a:
Diode
MOSFET
SCR
Zener diode
Explanation - MOSFETs require a gate voltage above Vgs(th) to turn on.
Correct answer is: MOSFET
Q.36 Which of the following is a typical thermal resistance value for a TO‑220 MOSFET package?
0.5 °C/W
1.5 °C/W
3.0 °C/W
10 °C/W
Explanation - TO‑220 packages often have a thermal resistance around 3 °C/W to the heat sink.
Correct answer is: 3.0 °C/W
Q.37 Which device type is most commonly used for controlled rectification in a power inverter?
IGBT
SCR
MOSFET
Zener diode
Explanation - IGBTs can be gate‑controlled to start conduction, making them suitable for inverters.
Correct answer is: IGBT
Q.38 In a high‑frequency switch‑mode power supply, which component primarily limits the switching frequency?
Diode reverse recovery time
Inductor value
MOSFET on‑resistance
Capacitor ESR
Explanation - Fast switching requires diodes with negligible reverse recovery to avoid losses.
Correct answer is: Diode reverse recovery time
Q.39 Which of the following is an example of a 'wide bandgap' semiconductor device?
Silicon MOSFET
GaN HEMT
SiC MOSFET
Both B and C
Explanation - Both GaN and SiC are wide bandgap materials used in high‑speed, high‑temperature devices.
Correct answer is: Both B and C
Q.40 Why are Schottky diodes preferred in low‑loss rectifiers?
Higher reverse voltage
Lower forward voltage drop
Fast reverse recovery
Higher current rating
Explanation - The low forward drop reduces conduction losses in high‑efficiency rectifiers.
Correct answer is: Lower forward voltage drop
Q.41 Which parameter determines the maximum continuous current a MOSFET can carry before overheating?
Id(max)
Vds(max)
Qg
Gate threshold voltage
Explanation - Id(max) is the maximum drain current specified for continuous operation.
Correct answer is: Id(max)
Q.42 The energy stored in the drain‑source capacitance during switching is referred to as:
Gate charge
Capacitance energy
Switching loss
On‑resistance loss
Explanation - This energy must be dissipated during the turn‑off transition.
Correct answer is: Capacitance energy
Q.43 What is the typical on‑time for a MOSFET gate during a single switching cycle?
Microseconds
Nanoseconds
Seconds
Minutes
Explanation - MOSFET gate switching occurs on the microsecond to nanosecond scale.
Correct answer is: Microseconds
Q.44 Which of the following is a common cause of thermal runaway in power MOSFETs?
High on‑resistance
High gate threshold voltage
Low reverse recovery time
Small package size
Explanation - High on‑resistance leads to higher conduction losses and heating, potentially causing runaway.
Correct answer is: High on‑resistance
Q.45 What does the 'Vgs(th)' rating indicate for a MOSFET?
Maximum gate‑source voltage
Minimum gate‑source voltage required to turn on
Gate threshold current
Gate oxide thickness
Explanation - Vgs(th) is the lowest gate voltage at which the MOSFET starts to conduct.
Correct answer is: Minimum gate‑source voltage required to turn on
Q.46 Which device is best suited for high‑frequency PWM control in LED drivers?
SCR
IGBT
MOSFET
Diode
Explanation - MOSFETs switch quickly with low losses, ideal for PWM in LED drivers.
Correct answer is: MOSFET
Q.47 A silicon MOSFET with an on‑resistance of 5 mΩ and a drain current of 10 A will dissipate how much conduction loss?
0.5 W
0.25 W
1 W
2 W
Explanation - Conduction loss = I²R = (10 A)² × 0.005 Ω = 0.5 W.
Correct answer is: 0.5 W
Q.48 Which parameter of a diode is directly related to its ability to block reverse voltage?
Reverse recovery time
Peak inverse voltage (PIV)
Forward current rating
Package type
Explanation - PIV specifies the maximum reverse voltage the diode can withstand.
Correct answer is: Peak inverse voltage (PIV)
Q.49 In a half‑bridge inverter, the two main switches are typically:
Two SCRs
Two MOSFETs
Two diodes
Two Zener diodes
Explanation - MOSFETs provide fast, low‑loss switching in half‑bridge inverters.
Correct answer is: Two MOSFETs
Q.50 What is the primary advantage of a SiC MOSFET over a standard silicon MOSFET?
Lower cost
Higher voltage and temperature capability
Larger size
Higher gate threshold voltage
Explanation - SiC devices operate at higher temperatures and voltages with lower losses.
Correct answer is: Higher voltage and temperature capability
Q.51 Which device is typically used as a thyristor in a controlled rectifier circuit?
SCR
IGBT
MOSFET
Triac
Explanation - An SCR is the standard thyristor used for controlled rectification.
Correct answer is: SCR
Q.52 Which parameter is most relevant when evaluating the thermal performance of a power device?
Gate threshold voltage
Thermal resistance from junction to case
Reverse recovery time
Package type
Explanation - Lower thermal resistance improves heat dissipation from the junction to the case.
Correct answer is: Thermal resistance from junction to case
Q.53 Which of the following is NOT a typical failure mode for power MOSFETs?
Latch‑up
Burnout due to over‑current
Gate oxide breakdown
Reverse recovery overheating
Explanation - Reverse recovery is relevant to diodes; MOSFETs do not exhibit this phenomenon.
Correct answer is: Reverse recovery overheating
Q.54 What is the main purpose of a snubber circuit across a power MOSFET?
To supply gate drive voltage
To reduce voltage spikes and ringing
To increase conduction losses
To block reverse current
Explanation - Snubbers limit dv/dt, protecting the device from over‑voltage transients.
Correct answer is: To reduce voltage spikes and ringing
Q.55 Which device type is most suitable for high‑frequency DC‑DC converters operating above 1 MHz?
IGBT
SiC MOSFET
GaN HEMT
SCR
Explanation - GaN HEMTs support very high switching speeds, ideal for > 1 MHz operation.
Correct answer is: GaN HEMT
Q.56 What is the typical duty cycle used in a 1 kHz PWM controller for a buck converter?
10 %
50 %
90 %
100 %
Explanation - A 50 % duty cycle provides a balance between output voltage and efficiency.
Correct answer is: 50 %
Q.57 Which parameter indicates the maximum allowable current during the turn‑off transition of a MOSFET?
Miller current
Gate charge
Reverse recovery current
On‑resistance
Explanation - Miller current refers to the current that flows during the Miller plateau, limiting turn‑off speed.
Correct answer is: Miller current
Q.58 When sizing a heat sink for a power MOSFET with a power dissipation of 30 W, which thermal resistance value is acceptable if the ambient temperature is 30 °C?
0.5 °C/W
1 °C/W
2 °C/W
5 °C/W
Explanation - With a 1 °C/W resistance, temperature rise is 30 °C, keeping junction temperature below 60 °C.
Correct answer is: 1 °C/W
Q.59 In high‑voltage MOSFETs, the term 'voltage blocking capability' refers to:
Gate threshold voltage
Drain‑source voltage rating
Reverse leakage current
On‑resistance
Explanation - Voltage blocking capability is the maximum Vds the device can tolerate.
Correct answer is: Drain‑source voltage rating
Q.60 Which device is most vulnerable to electrostatic discharge (ESD) during handling?
SCR
IGBT
MOSFET
Diode
Explanation - MOSFET gates are highly sensitive to static discharge, requiring careful handling.
Correct answer is: MOSFET
Q.61 The parameter 'Qg' of a MOSFET is used to estimate:
Conduction loss
Switching loss
Gate drive energy
Thermal resistance
Explanation - Qg represents the total gate charge needed to turn the device fully on/off.
Correct answer is: Gate drive energy
Q.62 Which of these is a common technique for reducing conduction losses in high‑current IGBT modules?
Using a higher Vds rating
Adding a series resistor
Selecting a low on‑resistance collector emitter path
Operating at lower temperatures
Explanation - Low on‑resistance paths minimize I²R losses in the module.
Correct answer is: Selecting a low on‑resistance collector emitter path
Q.63 Which factor primarily limits the maximum operating frequency of a power MOSFET?
Gate threshold voltage
On‑resistance
Gate charge and Miller capacitance
Drain‑source voltage rating
Explanation - High gate charge and Miller capacitance slow down switching, limiting frequency.
Correct answer is: Gate charge and Miller capacitance
Q.64 Which of the following is a key difference between an SCR and an IGBT?
SCR is controlled by gate, IGBT is not
SCR has a built‑in latch‑up protection, IGBT does not
IGBT uses a MOSFET gate and a BJT for conduction, SCR uses a triode structure
SCR can only conduct in one direction, IGBT can conduct in both
Explanation - IGBTs combine MOSFET and BJT features; SCRs are thyristors that require a gate trigger but maintain conduction indefinitely.
Correct answer is: IGBT uses a MOSFET gate and a BJT for conduction, SCR uses a triode structure
Q.65 In a switched‑mode power supply, what is the role of the freewheel diode?
To supply gate drive voltage
To provide a path for inductive current when the switch turns off
To regulate the output voltage
To block reverse current through the MOSFET
Explanation - The freewheel diode conducts when the switch opens, allowing the inductor to discharge safely.
Correct answer is: To provide a path for inductive current when the switch turns off
Q.66 Which of the following best describes the 'reverse recovery current' in a diode?
Current flowing in reverse during normal operation
Current during the transition from forward to reverse bias
Leakage current at high temperatures
Current in the diode's cathode during conduction
Explanation - Reverse recovery current flows as stored charge is removed during switching.
Correct answer is: Current during the transition from forward to reverse bias
Q.67 A 1 kW power module with a thermal resistance of 0.5 °C/W will reach what junction temperature if the ambient temperature is 40 °C?
40 °C
70 °C
100 °C
200 °C
Explanation - Temperature rise = Power × Thermal resistance = 1000 W × 0.5 °C/W = 500 °C; actual value unrealistic—this demonstrates the need for proper heat sinking.
Correct answer is: 70 °C
Q.68 Which parameter is commonly used to specify the maximum continuous duty cycle of a power transistor?
On‑resistance
Maximum drain current
Maximum continuous power dissipation
Gate threshold voltage
Explanation - Duty cycle is limited by the device's ability to dissipate power continuously.
Correct answer is: Maximum continuous power dissipation
Q.69 In designing a high‑voltage power supply, which factor primarily limits the selection of a MOSFET?
Gate threshold voltage
Maximum drain‑source voltage rating
Forward current rating
Package type
Explanation - The MOSFET must withstand the maximum voltage it will experience in the circuit.
Correct answer is: Maximum drain‑source voltage rating
Q.70 Which of the following is a common technique for improving the thermal performance of a SiC MOSFET module?
Use a larger gate resistor
Increase the on‑resistance
Add a heat sink with high thermal conductivity
Lower the operating frequency
Explanation - Heat sinks efficiently dissipate heat from the SiC module.
Correct answer is: Add a heat sink with high thermal conductivity
Q.71 When integrating a power MOSFET into a digital control circuit, which parameter determines the speed of the gate drive circuit?
Gate charge (Qg)
Drain‑source voltage
On‑resistance
Reverse recovery time
Explanation - Lower Qg allows faster charging/discharging of the gate, enabling faster switching.
Correct answer is: Gate charge (Qg)
Q.72 In a high‑efficiency inverter, why might a silicon MOSFET be replaced with a GaN device?
Higher cost
Lower switching losses at high frequencies
Higher on‑resistance
Higher gate threshold voltage
Explanation - GaN devices have negligible reverse recovery and low gate charge, reducing losses.
Correct answer is: Lower switching losses at high frequencies
Q.73 What is the main benefit of using a synchronous rectifier in a DC‑DC converter?
Simpler design
Increased conduction losses
Reduced diode reverse recovery loss
Higher reverse voltage rating
Explanation - The synchronous switch replaces the diode, eliminating reverse recovery losses.
Correct answer is: Reduced diode reverse recovery loss
Q.74 Which of the following is a design consideration for a power module that operates at 400 V DC?
Gate oxide thickness
Drain‑source voltage rating
Gate threshold voltage
Package color
Explanation - The device must be rated for at least 400 V to avoid breakdown.
Correct answer is: Drain‑source voltage rating
Q.75 When using a power MOSFET in a high‑current application, why is a heat sink necessary?
To reduce gate threshold voltage
To dissipate conduction and switching losses as heat
To increase the device's reverse voltage rating
To improve the device's thermal resistance to case
Explanation - Heat sinks help transfer heat away from the junction to maintain safe operating temperatures.
Correct answer is: To dissipate conduction and switching losses as heat
Q.76 Which parameter is most critical when selecting a gate driver for a high‑power IGBT?
Output voltage level
Maximum gate charge
On‑resistance
Package size
Explanation - The driver must supply the gate charge quickly to achieve fast switching.
Correct answer is: Maximum gate charge
Q.77 Which of the following represents a cutting‑edge semiconductor material used for next‑generation power devices?
Silicon carbide (SiC)
Gallium arsenide (GaAs)
Silicon (Si)
Germanium (Ge)
Explanation - SiC offers high voltage, temperature, and frequency performance for modern power electronics.
Correct answer is: Silicon carbide (SiC)
Q.78 What is the typical on‑resistance value of a 1200 V SiC MOSFET for a 100 A device?
5 mΩ
20 mΩ
50 mΩ
100 mΩ
Explanation - SiC devices achieve very low on‑resistance even at high voltage and current ratings.
Correct answer is: 5 mΩ
Q.79 Which property of GaN HEMT makes it suitable for RF power amplifiers?
High gate threshold voltage
High electron mobility
High on‑resistance
Large body diode area
Explanation - High electron mobility allows fast switching and high power handling at RF frequencies.
Correct answer is: High electron mobility
Q.80 What is the main advantage of using a SiC MOSFET over a GaN device in high‑voltage DC‑DC converters?
Lower cost
Higher maximum drain‑source voltage
Lower switching speed
Higher reverse recovery time
Explanation - SiC devices can handle voltages > 1 kV, which GaN devices typically cannot.
Correct answer is: Higher maximum drain‑source voltage
Q.81 In a power module, what does 'Tj' refer to?
Maximum ambient temperature
Junction temperature
Case temperature
Thermal resistance to ambient
Explanation - Tj is the temperature at the semiconductor junction.
Correct answer is: Junction temperature
Q.82 Which of the following is a key design challenge when using SiC devices in high‑frequency applications?
High on‑resistance
Large gate charge
High reverse recovery time
Low breakdown voltage
Explanation - SiC devices have significant gate charge, making fast switching energy demanding.
Correct answer is: Large gate charge
Q.83 What is the primary reason for using an ESD protection diode on the gate of a MOSFET?
To limit gate voltage during normal operation
To clamp voltage spikes from static discharge
To increase gate threshold voltage
To reduce reverse recovery losses
Explanation - ESD diodes protect the sensitive gate oxide from high‑voltage transients.
Correct answer is: To clamp voltage spikes from static discharge
Q.84 Which parameter indicates the maximum allowable gate current for a GaN HEMT?
Gate current limit
Gate charge
Maximum gate voltage
Drain‑source voltage rating
Explanation - GaN devices have a specified gate current limit to avoid damage.
Correct answer is: Gate current limit
Q.85 Which of the following best describes the 'on‑resistance' of a MOSFET?
Resistance between gate and source
Resistance between drain and source when on
Resistance between drain and gate
Resistance of the package to case
Explanation - On‑resistance is the small resistance the MOSFET presents while conducting.
Correct answer is: Resistance between drain and source when on
Q.86 In a power electronics system, the 'gate drive voltage' must exceed which parameter for proper operation?
Vds(max)
Vgs(th)
Id(max)
Qg
Explanation - Gate voltage must be above the threshold to turn the MOSFET fully on.
Correct answer is: Vgs(th)
Q.87 Which of the following is a typical application for an IGBT in automotive power electronics?
Headlight dimming
Motor control in electric vehicles
Audio amplifier
Lighting LEDs
Explanation - IGBTs handle high voltage and current required for motor drives.
Correct answer is: Motor control in electric vehicles
Q.88 What is the main function of a gate‑to‑source resistor in a MOSFET gate drive circuit?
Prevent over‑voltage at the drain
Control the turn‑on and turn‑off speed
Reduce reverse recovery time
Set the maximum gate current
Explanation - The resistor limits gate charging rate, affecting switching speed.
Correct answer is: Control the turn‑on and turn‑off speed
Q.89 Which of the following is a major benefit of using SiC MOSFETs in high‑temperature environments?
Higher gate threshold voltage
Lower on‑resistance at high temperature
Higher breakdown voltage at low temperature
Higher reverse recovery time
Explanation - SiC devices maintain low resistance even at elevated temperatures.
Correct answer is: Lower on‑resistance at high temperature
Q.90 In high‑power DC‑DC converters, why is the 'forward voltage drop' of a diode important?
It determines the diode's reverse voltage rating
It affects the efficiency of the converter
It sets the maximum current rating
It controls the switching frequency
Explanation - A lower forward drop reduces conduction losses and improves efficiency.
Correct answer is: It affects the efficiency of the converter
Q.91 What does the term 'reverse blocking voltage' refer to in the context of a MOSFET?
Maximum voltage that can be applied across gate‑source
Maximum voltage that can be applied across drain‑source in reverse bias
Voltage that must be exceeded to trigger turn‑off
Maximum voltage between drain and gate
Explanation - Reverse blocking voltage is the maximum Vds the device can withstand without breakdown.
Correct answer is: Maximum voltage that can be applied across drain‑source in reverse bias
Q.92 Which device is commonly used for high‑frequency power conversion in RF amplifiers?
SCR
IGBT
GaN HEMT
Diode
Explanation - GaN HEMTs provide high frequency operation with low losses.
Correct answer is: GaN HEMT
Q.93 Which of the following is a typical 'thermal resistance' metric used to assess heat sinking requirements?
Rds(on)
RθJC
Gate charge
Reverse recovery time
Explanation - RθJC is the thermal resistance from junction to case, important for heat sink design.
Correct answer is: RθJC