Thursday, July 24, 2025

EDC MCQ QUESTION WITH ANSWERS

 


UNIT 1


🔌 Rectifiers


1. What is the main purpose of a rectifier?

A) To increase voltage

B) To convert DC to AC

C) To convert AC to DC

D) To amplify signals

✅ Answer: C) To convert AC to DC



2. Which of the following uses only one diode?

A) Full-wave rectifier

B) Bridge rectifier

C) Half-wave rectifier

D) None of these

✅ Answer: C) Half-wave rectifier



3. In a full-wave rectifier, the output frequency is:

A) Equal to input

B) Half of input

C) Double the input

D) Zero

✅ Answer: C) Double the input



4. Bridge rectifier uses how many diodes?

A) 2

B) 3

C) 4

D) 6

✅ Answer: C) 4



5. What is the main advantage of a bridge rectifier over a center-tap rectifier?

A) More diodes used

B) Uses transformer

C) Requires no center tap

D) Expensive

✅ Answer: C) Requires no center tap





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✂️ Clippers and Clampers


6. Which component is essential in a clipper circuit?

A) Diode

B) Capacitor

C) Inductor

D) Transistor

✅ Answer: A) Diode



7. A positive clipper removes the:

A) Positive half of the waveform

B) Negative half of the waveform

C) Both halves

D) Does not remove any part

✅ Answer: A) Positive half of the waveform



8. Which clipper allows current flow in only one direction and clips voltage beyond a specific level?

A) Biased clipper

B) Unbiased clipper

C) Negative clipper

D) Zener clipper

✅ Answer: A) Biased clipper



9. The component responsible for fixing the clamping level in a clamper circuit is:

A) Diode

B) Resistor

C) Capacitor

D) Battery or voltage source

✅ Answer: D) Battery or voltage source



10. What does a positive clamper do to a waveform?

A) Raises it above the zero level

B) Clips the top portion

C) Lowers it below zero level

D) Removes negative half-cycle

✅ Answer: C) Lowers it below zero level



11. Which of the following is not a type of clipper?

A) Positive clipper

B) Negative clipper

C) Series clipper

D) Center clipper

✅ Answer: D) Center clipper



12. Clampers are used to:

A) Change peak voltage

B) Change DC level

C) Clip the signal

D) Amplify input

✅ Answer: B) Change DC level



13. The basic components of a clamper circuit include:

A) Diode and transformer

B) Resistor and capacitor

C) Diode, resistor, and capacitor

D) Inductor and diode

✅ Answer: C) Diode, resistor, and capacitor





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💡 Opto-Electronic Devices


14. Which diode emits light when forward biased?

A) Zener Diode

B) Photo-Diode

C) LED

D) Tunnel Diode

✅ Answer: C) LED



15. LED stands for:

A) Light Emitting Device

B) Light Emitting Diode

C) Linear Energy Diode

D) Low Energy Display

✅ Answer: B) Light Emitting Diode



16. Photo-diode operates in which biasing condition?

A) Forward bias

B) Reverse bias

C) Zero bias

D) Both

✅ Answer: B) Reverse bias



17. Photo-diode is used to:

A) Emit light

B) Regulate voltage

C) Detect light

D) Store charge

✅ Answer: C) Detect light



18. Which factor affects the intensity of light emitted by an LED?

A) Voltage drop

B) Temperature

C) Reverse current

D) Forward current

✅ Answer: D) Forward current



19. Which device generates current when exposed to light?

A) LED

B) Zener diode

C) Photo-diode

D) Varactor diode

✅ Answer: C) Photo-diode



20. In LED, the color of emitted light depends on:

A) Power supply


B) Current

C) Semiconductor material

D) Size of diode

✅ Answer: C) Semiconductor material


UNIT 2


⚙️ 1. BJT Basics & Working Principle


1. What does BJT stand for?

A) Bipolar Junction Terminal

B) Bipolar Junction Transistor

C) Bi-Junction Terminal

D) Bipolar Jet Transistor

✅ Answer: B) Bipolar Junction Transistor



2. Which of the following is a current-controlled device?

A) FET

B) MOSFET

C) BJT

D) UJT

✅ Answer: C) BJT



3. In an NPN transistor, the majority charge carriers are:

A) Holes

B) Electrons

C) Neutrons

D) Ions

✅ Answer: B) Electrons



4. What is the function of the base region in a BJT?

A) Acts as main current path

B) Controls the current flow

C) Blocks current

D) Stores energy

✅ Answer: B) Controls the current flow



5. In a PNP transistor, current flows from:

A) Collector to emitter

B) Base to collector

C) Emitter to collector

D) Collector to base

✅ Answer: C) Emitter to collector





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🔄 2. BJT Modes of Operation


6. Which BJT mode is used for amplification?

A) Cut-off

B) Saturation

C) Active

D) Reverse

✅ Answer: C) Active



7. In the cut-off region of a transistor:

A) Base-emitter junction is forward-biased

B) Collector current is maximum

C) Both junctions are reverse-biased

D) Base-collector junction is forward-biased

✅ Answer: C) Both junctions are reverse-biased



8. When a transistor is in saturation:

A) Acts as an amplifier

B) Acts as an insulator

C) Acts as a switch (ON)

D) No current flows

✅ Answer: C) Acts as a switch (ON)



9. In active mode, the base-emitter junction is:

A) Reverse-biased

B) Forward-biased

C) No bias

D) Short-circuited

✅ Answer: B) Forward-biased



10. In which mode does a BJT act as a switch (OFF)?

A) Active

B) Saturation

C) Cut-off

D) Breakdown

✅ Answer: C) Cut-off


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🧩 3. Transistor Configurations


11. Which transistor configuration gives high voltage gain?

A) Common Collector

B) Common Base

C) Common Emitter

D) All of the above

✅ Answer: C) Common Emitter



12. Which configuration is best for impedance matching?

A) Common Emitter

B) Common Base

C) Common Collector

D) None

✅ Answer: C) Common Collector



13. In CB configuration, the input is between:

A) Collector and base

B) Emitter and base

C) Base and emitter

D) Collector and emitter

✅ Answer: B) Emitter and base



14. In CE configuration, the output is taken from:

A) Emitter

B) Base

C) Collector

D) Ground

✅ Answer: C) Collector



15. Which configuration has unity current gain?

A) Common Emitter

B) Common Base

C) Common Collector

D) Both B and C

✅ Answer: B) Common Base





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⚡ 4. Transistor Biasing


16. Why is biasing necessary in a transistor circuit?

A) To turn it off

B) To change resistance

C) To fix the operating point

D) To reduce noise

✅ Answer: C) To fix the operating point



17. The ratio of change in collector current to change in base current is called:

A) Alpha

B) Beta

C) Stability factor

D) Gain

✅ Answer: B) Beta



18. Which biasing method gives best stability?

A) Fixed bias

B) Collector-to-base bias

C) Voltage divider bias

D) Base resistor bias

✅ Answer: C) Voltage divider bias



19. Which of the following biasing circuits requires the least components?

A) Voltage divider

B) Fixed bias

C) Emitter feedback

D) Collector feedback

✅ Answer: B) Fixed bias



20. Stability factor (S) indicates:

A) Temperature resista

nce

B) Gain

C) Output power

D) Sensitivity to IC changes

✅ Answer: D) Sensitivity to IC changes


UNIT 3


🔌 1. Transistor as Amplifier and Switch


1. What does a transistor do in an amplifier circuit?

A) Blocks current

B) Increases signal strength

C) Acts as a filter

D) Stores energy

✅ Answer: B) Increases signal strength



2. When a transistor is used as a switch, in which regions does it operate?

A) Cut-off and Active

B) Active and Saturation

C) Saturation and Cut-off

D) Breakdown and Active

✅ Answer: C) Saturation and Cut-off



3. In the CE amplifier, the input is applied between:

A) Base and Collector

B) Emitter and Collector

C) Base and Emitter

D) Collector and Ground

✅ Answer: C) Base and Emitter



4. Which amplifier configuration offers both voltage and current gain?

A) Common Base

B) Common Collector

C) Common Emitter

D) None

✅ Answer: C) Common Emitter



5. What phase relationship exists between input and output in a CE amplifier?

A) 0°

B) 90°

C) 180°

D) 360°

✅ Answer: C) 180°





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🎚️ 2. RC Coupled Amplifier


6. RC coupled amplifiers are mainly used for:

A) Power amplification

B) Low-frequency amplification

C) Radio transmission

D) High voltage control

✅ Answer: B) Low-frequency amplification



7. What is the main coupling element between stages in an RC coupled amplifier?

A) Transformer

B) Capacitor

C) Inductor

D) Diode

✅ Answer: B) Capacitor



8. Which is a disadvantage of RC coupled amplifiers?

A) Poor frequency response

B) High cost

C) Low power gain

D) Bulky design

✅ Answer: C) Low power gain



9. What is the bandwidth of an RC coupled amplifier dependent on?

A) Base resistor

B) Coupling capacitor and load

C) Supply voltage

D) Collector resistor

✅ Answer: B) Coupling capacitor and load



10. RC coupled amplifier gives maximum gain in which frequency range?

A) Low

B) Mid

C) High

D) Very high

✅ Answer: B) Mid





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🔊 3. Power Amplifiers


11. Which class of power amplifier has the highest efficiency?

A) Class A

B) Class B

C) Class C

D) Class AB

✅ Answer: C) Class C



12. Which amplifier has output for the full 360° of the input cycle?

A) Class A

B) Class B

C) Class C

D) Class D

✅ Answer: A) Class A



13. Which power amplifier operates only for 180° of the input signal?

A) Class A

B) Class B

C) Class C

D) Class AB

✅ Answer: B) Class B



14. What is the major drawback of Class B amplifier?

A) Low gain

B) High distortion

C) Cross-over distortion

D) High cost

✅ Answer: C) Cross-over distortion



15. Which amplifier configuration helps eliminate cross-over distortion?

A) Class A

B) Class B

C) Push-pull

D) Cascode

✅ Answer: C) Push-pull





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🧩 4. Multistage & Special Amplifiers


16. The purpose of using multistage amplifiers is to:

A) Reduce gain

B) Improve stability

C) Increase overall gain

D) Reduce power consumption

✅ Answer: C) Increase overall gain



17. What is a Darlington pair known for?

A) Low gain

B) High current gain

C) High voltage gain

D) Low input impedance

✅ Answer: B) High current gain



18. Cascode amplifier is a combination of:

A) Two CE amplifiers

B) CE and CB amplifiers

C) CB and CC amplifiers

D) CE and CC amplifiers

✅ Answer: B) CE and CB amplifiers



19. In a cascade amplifier, the output of one stage is:

A) Input to the power supply

B) Fed back to the input

C) Input to the next stage

D) Grounded

✅ Answer: C) Input to the next stage



20. CMRR is associated with which amplifier?

A) Class B


B) RC Coupled

C) Differential

D) Power

✅ Answer: C) Differential


UNIT 4


🔁 1. Feedback Amplifiers


1. What is feedback in an amplifier circuit?

A) Adding noise

B) Sending part of the output to input

C) Boosting power supply

D) Disconnecting input

✅ Answer: B) Sending part of the output to input



2. Which of the following is a type of feedback?

A) Linear and Nonlinear

B) Series and Parallel

C) Positive and Negative

D) Direct and Indirect

✅ Answer: C) Positive and Negative



3. What is the effect of negative feedback on bandwidth?

A) Decreases it

B) No effect

C) Increases it

D) Reverses polarity

✅ Answer: C) Increases it



4. Negative feedback in amplifiers improves:

A) Distortion

B) Noise

C) Stability

D) Input voltage

✅ Answer: C) Stability



5. Which type of feedback reduces gain but increases linearity?

A) Positive

B) Negative

C) Regenerative

D) Capacitive

✅ Answer: B) Negative



6. The four types of negative feedback amplifiers are based on:

A) Current and voltage feedback

B) Biasing methods

C) Resistor values

D) Capacitance type

✅ Answer: A) Current and voltage feedback



7. Negative feedback reduces:

A) Input resistance

B) Output resistance

C) Bandwidth

D) Distortion

✅ Answer: D) Distortion



8. In a voltage series feedback amplifier, the feedback is taken from:

A) Output current

B) Input voltage

C) Output voltage

D) Input current

✅ Answer: C) Output voltage





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🌀 2. Theory of Oscillation


9. Which circuit stores energy in both inductor and capacitor?

A) Amplifier

B) Tank Circuit

C) Filter

D) Transformer

✅ Answer: B) Tank Circuit



10. Which is a basic condition for oscillation?

A) Zero gain

B) Infinite feedback

C) Barkhausen criterion

D) No input

✅ Answer: C) Barkhausen criterion



11. The Barkhausen criterion requires:

A) Loop gain = 0

B) Loop gain > 1

C) Loop gain = 1 with 0° phase shift

D) Output voltage = 0

✅ Answer: C) Loop gain = 1 with 0° phase shift



12. Oscillators are classified based on:

A) Frequency range

B) Phase difference

C) Feedback used

D) Type of wave generated

✅ Answer: C) Feedback used





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🔊 3. Oscillator Circuits


13. Which oscillator uses a tapped inductor for frequency determination?

A) Colpitts

B) Hartley

C) Wien Bridge

D) Crystal

✅ Answer: B) Hartley



14. In a Colpitts oscillator, feedback is derived from:

A) Resistors

B) Inductors

C) Capacitor voltage divider

D) Transformer

✅ Answer: C) Capacitor voltage divider



15. The RC Phase Shift Oscillator uses how many RC sections?

A) 1

B) 2

C) 3

D) 4

✅ Answer: C) 3



16. Wien bridge oscillator is commonly used to generate:

A) Sawtooth wave

B) Sine wave

C) Square wave

D) Triangular wave

✅ Answer: B) Sine wave



17. Which component provides stability in a Crystal Oscillator?

A) Capacitor

B) Inductor

C) Resistor

D) Quartz crystal

✅ Answer: D) Quartz crystal



18. Hartley oscillator uses which components to determine frequency?

A) R and C

B) L and C

C) Only R

D) Only C

✅ Answer: B) L and C



19. Which oscillator is most stable in frequency?

A) Hartley

B) RC Phase Shift

C) Wien Bridge

D) Crystal

✅ Answer: D) Crystal



20. Oscillator circuits generate output without:

A) Power supply

B) Input signal

C) Gr

ound connection

D) Feedback

✅ Answer: B) Input signal


UNIT 5


🔷 1. FET Basics

  1. What does FET stand for?
    A) Field Emission Transistor
    B) Field Energy Transistor
    C) Field Effect Transistor
    D) Fixed Electron Transistor
    Answer: C) Field Effect Transistor

  2. FETs are classified into:
    A) BJT and JFET
    B) JFET and MOSFET
    C) UJT and BJT
    D) SCR and TRIAC
    Answer: B) JFET and MOSFET

  3. The input impedance of FET is:
    A) Very low
    B) Moderate
    C) High
    D) Zero
    Answer: C) High

  4. FET is controlled by:
    A) Current
    B) Voltage
    C) Power
    D) Resistance
    Answer: B) Voltage

  5. Which terminal controls the flow of current in JFET?
    A) Drain
    B) Source
    C) Gate
    D) Body
    Answer: C) Gate


🧿 2. JFET – Junction Field Effect Transistor

  1. In N-channel JFET, the majority carriers are:
    A) Holes
    B) Electrons
    C) Protons
    D) Neutrons
    Answer: B) Electrons

  2. The characteristic curve of JFET is called:
    A) Load line
    B) Transfer curve
    C) Output curve
    D) Saturation curve
    Answer: B) Transfer curve

  3. The region where JFET operates as a constant current source is:
    A) Cut-off
    B) Ohmic
    C) Active
    D) Saturation
    Answer: D) Saturation

  4. Pinch-off voltage in a JFET is the voltage at which:
    A) The current becomes zero
    B) Gate current starts flowing
    C) Channel is fully open
    D) Current becomes constant
    Answer: D) Current becomes constant

  5. JFET has how many terminals?
    A) 2
    B) 3
    C) 4
    D) 5
    Answer: B) 3


⚙️ 3. MOSFET – Metal Oxide Semiconductor FET

  1. MOSFET has how many operating modes?
    A) 2
    B) 3
    C) 4
    D) 5
    Answer: A) 2 (Enhancement and Depletion)

  2. In N-channel Enhancement mode MOSFET, the channel is formed:
    A) At zero gate voltage
    B) By forward biasing gate
    C) When V_GS exceeds threshold
    D) At negative voltage
    Answer: C) When V_GS exceeds threshold

  3. The key difference between JFET and MOSFET is:
    A) Gate is insulated in MOSFET
    B) MOSFET has lower gain
    C) JFET uses holes as carriers
    D) JFET is faster
    Answer: A) Gate is insulated in MOSFET

  4. The substrate terminal in a MOSFET is also known as:
    A) Base
    B) Drain
    C) Body
    D) Channel
    Answer: C) Body

  5. Which MOSFET can operate with both positive and negative gate voltage?
    A) Depletion-mode
    B) Enhancement-mode
    C) BJT
    D) IGBT
    Answer: A) Depletion-mode


🌀 4. UJT – Uni Junction Transistor

  1. How many junctions does a UJT have?
    A) 1
    B) 2
    C) 3
    D) 4
    Answer: A) 1

  2. The UJT is mainly used as a:
    A) Amplifier
    B) Comparator
    C) Oscillator
    D) Switch
    Answer: C) Oscillator

  3. UJT has how many terminals?
    A) 2
    B) 3
    C) 4
    D) 5
    Answer: B) 3 (Emitter, Base1, Base2)

  4. The UJT relaxation oscillator produces which waveform?
    A) Sinusoidal
    B) Triangular
    C) Sawtooth
    D) Square
    Answer: C) Sawtooth

  5. The UJT is a:
    A) Voltage-controlled device
    B) Current-controlled device
    C) Temperature-controlled
    D) Resistance-controlled
    Answer: A) Voltage-controlled device


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EDC MCQ QUESTION WITH ANSWERS

  UNIT 1 🔌 Rectifiers 1. What is the main purpose of a rectifier? A) To increase voltage B) To convert DC to AC C) To convert AC to DC D) T...