FE Electrical – Electronics_medium_difficulty

#1. A photodiode operates in:

Forward bias for maximum sensitivity

Reverse bias for fast response

Zero bias only

Breakdown region

#2. The current gain β (hFE) of a BJT relates:

IC to IE

VCE to VBE

IB to IE

IC to IB

#3. In active mode operation of a BJT:

Both junctions are reverse biased

Both junctions are forward biased

BE junction forward biased, BC junction reverse biased

BE junction reverse biased, BC junction forward biased

#4. A boost converter:

Steps down voltage

Steps up voltage

Inverts voltage

Provides isolation

#5. A thermistor differs from RTD in that it has:

Linear response

Constant resistance

No temperature sensitivity

Highly nonlinear response with large sensitivity

#6. An analog multiplier IC performs:

Addition

Square root

Division only

Vout proportional to product of two inputs

#7. A DAC using an R-2R ladder network requires:

Many different resistor values

Capacitors

Only two resistor values (R and 2R)

Inductors

#8. An inverter converts:

DC to AC

AC to DC

AC to AC

DC to DC

#9. A voltage regulator maintains constant output despite:

Load changes only

Input voltage changes only

Neither

Both load and input voltage changes

#10. An LVDT transducer measures:

Temperature

Linear displacement

Pressure

Light intensity

#11. The average DC output of a full-wave rectifier with peak input Vm is:

Vm/π

2Vm/π

Vm/2

Vm

#12. In a switching power supply, efficiency is typically:

30-40%

50-60%

80-95%

100%

#13. A comparator is an op-amp operated:

In open-loop (no feedback)

With negative feedback

With positive feedback only

In linear region

#14. Crossover distortion in Class B amplifier occurs:

Near zero crossing of signal

At peak output

At any signal level

Only at high frequencies

#15. The transconductance gm of a MOSFET is defined as:

ΔID/ΔVDS

ΔVDS/ΔID

ΔVGS/ΔID

ΔID/ΔVGS

#16. Class A amplifier conducts for:

Half cycle

Less than half cycle

Quarter cycle

Full cycle

#17. Once triggered, an SCR turns off when:

Gate signal is removed

Anode current falls below holding current

Reverse gate pulse applied

Voltage increases

#18. A peak detector circuit holds:

Average value of signal

Maximum (peak) value of signal

Minimum value

RMS value

#19. A differentiator circuit using an op-amp has:

Capacitor in feedback

Inductor at input

Only resistors

Capacitor at input

#20. The gain-bandwidth product of an op-amp is:

Constant for a given device

Variable with frequency

Infinite

Zero at high frequency

#21. A thyristor (SCR) turns on when:

Gate signal is negative

Positive gate pulse and forward-biased anode

Reverse biased

No gate signal

#22. A TRIAC is equivalent to:

Two SCRs in anti-parallel

Two diodes in parallel

A transistor

A diode bridge

#23. A snubber circuit across a switch is used to:

Limit voltage spikes and dv/dt stress

Increase switching speed

Increase current

Reduce efficiency

#24. A buck converter:

Steps up voltage

Steps down voltage

Inverts voltage

Isolates input from output

#25. A 7805 voltage regulator provides:

5V adjustable output

-5V fixed output

+5V fixed output

+8.05V output

#26. The voltage gain of a common-source MOSFET amplifier is approximately:

gm/RD

1

-gm × RD

RD/gm

#27. Push-pull amplifier configuration uses:

Two transistors handling opposite half-cycles

Diodes only

Four transistors

Single transistor

#28. The dynamic resistance of a forward-biased diode at 1 mA (at room temperature) is approximately:

26 Ω

260 Ω

2.6 Ω

0.26 Ω

#29. An NPN transistor conducts when:

Collector is negative

Base is negative with respect to emitter

Base is positive with respect to emitter

Emitter is positive with respect to base

#30. A unity-gain buffer (voltage follower) has the configuration:

Open loop

Output connected to non-inverting input

Both inputs connected

Output connected to inverting input

#31. Hysteresis in a Schmitt trigger:

Provides noise immunity with two threshold levels

Creates oscillation

Increases gain

Reduces bandwidth

#32. An RTD (Resistance Temperature Detector) measures temperature using:

Frequency change

Current generation

Resistance change with temperature

Voltage generation

#33. An integrator circuit using an op-amp has:

Inductor in feedback

Only resistors

Capacitor in feedback

Capacitor at input

#34. The slew rate of an op-amp defines:

Bandwidth

Maximum rate of output voltage change

Input impedance

Maximum voltage gain

#35. A common-collector (emitter follower) amplifier has:

Low voltage and current gain

High voltage gain, low current gain

High voltage gain, high current gain

Voltage gain ≈ 1, high current gain

#36. A Zener diode is designed to operate in:

Saturation region

Forward bias region

Cutoff region

Reverse breakdown region

#37. The ripple frequency of a full-wave rectifier with 60 Hz input is:

120 Hz

30 Hz

60 Hz

180 Hz

#38. The total harmonic distortion (THD) measures:

Ratio of harmonic content to fundamental

Efficiency

Fundamental frequency

DC content

#39. The ripple factor is defined as:

Peak/Average ratio

DC voltage

DC/AC ratio

AC(rms)/DC ratio

#40. A strain gauge typically uses a:

Wheatstone bridge

Voltage divider

Op-amp only

Diode bridge

#41. A thermocouple measures temperature by:

Capacitance change

Resistance change

Seebeck effect (voltage from temperature difference)

Inductance change

#42. The main purpose of a bypass capacitor in a common-emitter amplifier is to:

Provide AC ground at emitter to increase gain

Couple stages

Block DC

Filter power supply

#43. Class B amplifier conducts for:

Quarter cycle

More than half cycle

Full cycle

Half cycle

#44. An instrumentation amplifier is characterized by:

High input impedance and adjustable differential gain

Single op-amp

Low CMRR

Unity gain only

#45. An n-channel enhancement MOSFET requires:

VGS > VTH (positive threshold) to conduct

VGS = 0 to conduct

VGS < 0 to conduct

Negative VDS

#46. An optocoupler provides:

Frequency conversion

Current gain

Electrical isolation between circuits

Voltage gain

#47. A phase-locked loop (PLL) consists of:

Only phase detector

Amplifier only

Only oscillator

Phase detector, loop filter, and VCO

#48. A flash ADC is characterized by:

Low power consumption

Single comparator

Very fast conversion, many comparators

Slow conversion

#49. A gyrator circuit can simulate:

Nothing useful

Capacitance using inductance

Resistance using capacitance

Inductance using capacitance and op-amps

#50. A single-phase full-bridge inverter uses how many switches?

6

2

4

8

#51. In a non-inverting op-amp configuration with Rf = 90 kΩ and R1 = 10 kΩ, the closed-loop gain is:

10

9

-10

-9

#52. In an inverting op-amp configuration with Rf = 100 kΩ and Rin = 10 kΩ, the closed-loop gain is:

-10

10

-100

11

#53. An active low-pass filter using op-amp compared to passive RC filter has:

Same performance

Lower gain

Gain capability and better performance

Worse frequency response

#54. A MOSFET operates in saturation (active) region when:

VGS = 0

VDS ≥ VGS – VTH

VDS < VGS – VTH

VGS < VTH

#55. The relationship between α and β of a BJT is:

α = β/(1+β)

Both A and B

β = 1-α

β = α/(1-α)

#56. A VCO (Voltage-Controlled Oscillator) produces:

Amplitude proportional to input

Constant frequency output

Frequency proportional to input voltage

DC output

#57. An LED emits light when:

Unbiased

Reverse biased

Forward biased

In breakdown

#58. The Miller effect in amplifiers refers to:

Bandwidth increase

Input capacitance multiplication due to voltage gain

Current gain increase

Output resistance increase

#59. A Darlington pair provides:

Low current gain

Very high current gain (β1 × β2)

Voltage gain

Power gain only

#60. In a forward-biased silicon diode, the typical voltage drop is approximately:

1.2 V

0.3 V

0.7 V

2.0 V

#61. A successive approximation ADC has conversion time that is:

Random

Proportional to input voltage

Fixed (proportional to bit count)

Instantaneous

#62. The reverse saturation current of a diode:

Is independent of temperature

Decreases with temperature

Equals forward current

Increases with temperature

#63. A summing amplifier with three inputs produces output:

Average of inputs

Product of inputs

Weighted sum of inputs (inverted)

Maximum of inputs

#64. Space vector modulation (SVM) is used in:

DC motors

Three-phase inverter control

Single-phase rectifiers

Linear regulators

#65. In a common-emitter amplifier, the output voltage is:

90° out of phase

In phase with input

180° out of phase with input

45° out of phase

#66. The resolution of a 10-bit ADC with 5V range is:

4.88 mV

10 mV

5 mV

0.5 mV

#67. The virtual ground concept in an inverting op-amp means:

Output is at ground

The inverting input is at ground potential (0V)

The inverting input is connected to ground

No current flows

#68. Shoot-through in H-bridge refers to:

Slow speed operation

Normal operation

Motor reversal

Both high and low side switches on simultaneously (short circuit)

#69. The input impedance of a common-base amplifier is:

Very low

High

Medium

Infinite

#70. In data acquisition, the sample-and-hold circuit is placed:

After the DAC

Before the ADC

After the ADC

Before the sensor

#71. PWM (Pulse Width Modulation) in switching regulators controls:

Switching frequency

Input current

Duty cycle to regulate output voltage

Output frequency

#72. The maximum theoretical efficiency of Class B amplifier is:

100%

50%

25%

78.5%

#73. The quality factor Q of a bandpass filter determines:

Stability

Bandwidth (sharpness of peak)

Phase shift

DC gain

#74. A buck-boost converter can:

Only step down

Only step up

Only invert

Both step up and step down

#75. Negative feedback in amplifiers:

Only affects phase

Increases gain and distortion

Has no effect

Decreases gain but improves stability and bandwidth

#76. A precision rectifier using op-amp improves upon diode rectifier by:

Reducing component count

Increasing current capacity

Increasing frequency response

Eliminating diode voltage drop effect

#77. A Sallen-Key filter topology is commonly used for:

High-power filters

First-order filters only

Passive filters

Second-order active filters

#78. Soft switching in power electronics refers to:

Hard turn-on

Zero-voltage or zero-current switching for reduced losses

High frequency switching

Slow switching

#79. Class AB amplifier is designed to:

Eliminate crossover distortion while improving efficiency

Provide maximum gain

Maximize efficiency

Operate at maximum power

#80. A three-phase inverter uses how many switches?

12

4

3

6

#81. A bridge rectifier uses how many diodes?

6

2

1

4

#82. Dead time in switching circuits prevents:

Shoot-through by ensuring switches don’t overlap

Current flow

Normal switching

Voltage regulation

#83. If a BJT has β = 100 and IC = 5 mA, the base current is:

0.05 mA

0.5 mA

50 µA

5 mA

#84. A half-wave rectifier conducts for:

Quarter cycle

Never

Full cycle

Half of each cycle

#85. Adding a filter capacitor to a rectifier:

Reduces ripple, smooths DC output

Increases ripple

Decreases DC output

Has no effect

#86. An ideal operational amplifier has:

Limited common-mode rejection

Finite gain and bandwidth

Equal input impedances

Infinite input impedance, zero output impedance

#87. The maximum theoretical efficiency of Class A amplifier is:

100%

50%

25%

78.5%

#88. The common-mode rejection ratio (CMRR) measures:

Ability to reject signals common to both inputs

Gain for common signals

Differential gain only

Bandwidth

#89. In an H-bridge motor driver, to make the motor rotate forward:

All switches off

All switches on

Diagonal pairs of switches activated

One switch only

#90. The forward voltage drop of a silicon diode is approximately:

0.3V

0.7V

1.2V

2.0V

#91. In a common-emitter amplifier, the output is:

In phase with input

180° out of phase

90° out of phase

45° out of phase

#92. The input impedance of an ideal op-amp is:

Zero

50Ω

1kΩ

Infinite

#93. A full-wave rectifier has output frequency _____ times the input frequency:

0.5

1

2

4

#94. The transconductance gm of a MOSFET relates:

VGS to ID

VDS to ID

Change in ID to change in VGS

VGS to VDS

#95. An inverting amplifier with Rf=100kΩ and Ri=10kΩ has gain:

10

-10

11

-11

#96. The bandwidth-gain product of an op-amp is:

Variable

Constant

Zero at DC

Infinite

#97. A zener diode operates in:

Forward bias

Cutoff region

Active region

Reverse breakdown

#98. The CMRR of an op-amp measures its ability to:

Amplify common-mode signals

Increase gain

Reject common-mode signals

Reduce offset

#99. A buck converter produces output voltage that is:

Higher than input

Equal to input

Lower than input

Negative of input

#100. The Early effect in BJTs causes:

Decreased β

Lower thermal noise

Increased breakdown voltage

Output resistance variation

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#1. A photodiode operates in:

#2. The current gain β (hFE) of a BJT relates:

#3. In active mode operation of a BJT:

#4. A boost converter:

#5. A thermistor differs from RTD in that it has:

#6. An analog multiplier IC performs:

#7. A DAC using an R-2R ladder network requires:

#8. An inverter converts:

#9. A voltage regulator maintains constant output despite:

#10. An LVDT transducer measures:

#11. The average DC output of a full-wave rectifier with peak input Vm is:

#12. In a switching power supply, efficiency is typically:

#13. A comparator is an op-amp operated:

#14. Crossover distortion in Class B amplifier occurs:

#15. The transconductance gm of a MOSFET is defined as:

#16. Class A amplifier conducts for:

#17. Once triggered, an SCR turns off when:

#18. A peak detector circuit holds:

#19. A differentiator circuit using an op-amp has:

#20. The gain-bandwidth product of an op-amp is:

#21. A thyristor (SCR) turns on when:

#22. A TRIAC is equivalent to:

#23. A snubber circuit across a switch is used to:

#24. A buck converter:

#25. A 7805 voltage regulator provides:

#26. The voltage gain of a common-source MOSFET amplifier is approximately:

#27. Push-pull amplifier configuration uses:

#28. The dynamic resistance of a forward-biased diode at 1 mA (at room temperature) is approximately:

#29. An NPN transistor conducts when:

#30. A unity-gain buffer (voltage follower) has the configuration:

#31. Hysteresis in a Schmitt trigger:

#32. An RTD (Resistance Temperature Detector) measures temperature using:

#33. An integrator circuit using an op-amp has:

#34. The slew rate of an op-amp defines:

#35. A common-collector (emitter follower) amplifier has:

#36. A Zener diode is designed to operate in:

#37. The ripple frequency of a full-wave rectifier with 60 Hz input is:

#38. The total harmonic distortion (THD) measures:

#39. The ripple factor is defined as:

#40. A strain gauge typically uses a:

#41. A thermocouple measures temperature by:

#42. The main purpose of a bypass capacitor in a common-emitter amplifier is to:

#43. Class B amplifier conducts for:

#44. An instrumentation amplifier is characterized by:

#45. An n-channel enhancement MOSFET requires:

#46. An optocoupler provides:

#47. A phase-locked loop (PLL) consists of:

#48. A flash ADC is characterized by:

#49. A gyrator circuit can simulate:

#50. A single-phase full-bridge inverter uses how many switches?

#51. In a non-inverting op-amp configuration with Rf = 90 kΩ and R1 = 10 kΩ, the closed-loop gain is:

#52. In an inverting op-amp configuration with Rf = 100 kΩ and Rin = 10 kΩ, the closed-loop gain is:

#53. An active low-pass filter using op-amp compared to passive RC filter has:

#54. A MOSFET operates in saturation (active) region when:

#55. The relationship between α and β of a BJT is:

#56. A VCO (Voltage-Controlled Oscillator) produces:

#57. An LED emits light when:

#58. The Miller effect in amplifiers refers to:

#59. A Darlington pair provides:

#60. In a forward-biased silicon diode, the typical voltage drop is approximately:

#61. A successive approximation ADC has conversion time that is:

#62. The reverse saturation current of a diode:

#63. A summing amplifier with three inputs produces output:

#64. Space vector modulation (SVM) is used in:

#65. In a common-emitter amplifier, the output voltage is:

#66. The resolution of a 10-bit ADC with 5V range is:

#67. The virtual ground concept in an inverting op-amp means:

#68. Shoot-through in H-bridge refers to:

#69. The input impedance of a common-base amplifier is:

#70. In data acquisition, the sample-and-hold circuit is placed:

#71. PWM (Pulse Width Modulation) in switching regulators controls:

#72. The maximum theoretical efficiency of Class B amplifier is:

#73. The quality factor Q of a bandpass filter determines:

#74. A buck-boost converter can:

#75. Negative feedback in amplifiers:

#76. A precision rectifier using op-amp improves upon diode rectifier by:

#77. A Sallen-Key filter topology is commonly used for:

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