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

---

✂️ 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

---

💡 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

---

🔄 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

---

🧩 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

---

⚡ 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°

---

🎚️ 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

---

🔊 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

---

🧩 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

---

🌀 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

---

🔊 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

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

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

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

9. 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

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

---

⚙️ 3. MOSFET – Metal Oxide Semiconductor FET

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

12. 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

13. 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

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

15. 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

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

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

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

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

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

ECE DE MCQ QUESTION WITH ANSWER

 

ECE - DE - MCQ

UNIT 1

🔢 Number System and Codes

1. What is the decimal equivalent of binary number 1101?
   A) 11
   B) 13
   C) 14
   D) 15
   ✅ Answer: B) 13

2. Convert (45)₁₀ to binary:
   A) 101101
   B) 110101
   C) 101011
   D) 110011
   ✅ Answer: A) 101101

3. What is the hexadecimal representation of (255)₁₀?
   A) FE
   B) FF
   C) F0
   D) F1
   ✅ Answer: B) FF

4. (111101)₂ is equivalent to which octal number?
   A) 75
   B) 77
   C) 65
   D) 61
   ✅ Answer: A) 75

5. What is 1's complement of binary number 100101?
   A) 011010
   B) 100010
   C) 011011
   D) 101010
   ✅ Answer: A) 011010

6. 2's complement of 1100 is:
   A) 0011
   B) 0100
   C) 1111
   D) 0101
   ✅ Answer: D) 0101

7. Perform binary addition: 1011 + 1101 = ?
   A) 11000
   B) 10100
   C) 10000
   D) 11110
   ✅ Answer: A) 11000

8. Binary subtraction: 10010 - 01001 = ?
   A) 01001
   B) 10001
   C) 01101
   D) 11111
   ✅ Answer: A) 01001

9. What is the BCD code for decimal number 39?
   A) 0011 1001
   B) 0100 0011
   C) 0011 0110
   D) 0111 0011
   ✅ Answer: A) 0011 1001

10. Which ASCII code represents the character 'A'?
    A) 65
    B) 66
    C) 67
    D) 64
    ✅ Answer: A) 65

11. What is the Gray code for binary number 1010?
    A) 1111
    B) 1110
    C) 1100
    D) 1001
    ✅ Answer: B) 1110

---

🔣 Boolean Algebra and K-Map

12. According to Boolean algebra, A + A = ?
    A) 1
    B) A
    C) 0
    D) A'
    ✅ Answer: B) A

13. Which is DeMorgan’s First Theorem?
    A) (A + B)' = A'B'
    B) (AB)' = A' + B'
    C) (A + B)' = A + B
    D) A' + B' = (AB)'
    ✅ Answer: A) (A + B)' = A'B'

14. The expression AB + A'C is in which form?
    A) POS
    B) SOP
    C) Canonical SOP
    D) Canonical POS
    ✅ Answer: B) SOP

15. Which Boolean expression represents the POS form?
    A) AB + AC
    B) (A + B)(A + C)
    C) A + B + C
    D) ABC + A'B'C'
    ✅ Answer: B) (A + B)(A + C)

16. What is the simplified form of A + AB using Boolean algebra?
    A) A
    B) AB
    C) B
    D) A + B
    ✅ Answer: A) A

17. What is the value of A ⊕ B (A XOR B) when A = 1 and B = 1?
    A) 1
    B) 0
    C) A
    D) B
    ✅ Answer: B) 0

18. In 4-variable K-map, how many cells are there?
    A) 4
    B) 8
    C) 16
    D) 32
    ✅ Answer: C) 16

19. In K-map, adjacent cells differ by:
    A) 2 bits
    B) 1 bit
    C) 3 bits
    D) No bits
    ✅ Answer: B) 1 bit

20. Simplify using K-map: F(A, B, C) = Σ(1, 2, 3, 7)
    A) A'C + AC
    B) B + C
    C) A + B
    D) AB + BC
    ✅ Answer: A) A'C + AC

UNIT 2

🔘 Logic Gates – Symbols, Expressions, Truth Tables

1. Which logic gate has the output expression Y = A · B?

A) OR

B) AND

C) XOR

D) NOT

✅ Answer: B) AND

2. What is the output of an OR gate when both inputs are 0?

A) 1

B) 0

C) A

D) B

✅ Answer: B) 0

3. The NOT gate is also known as a:

A) Inverter

B) Repeater

C) Comparator

D) Amplifier

✅ Answer: A) Inverter

4. Which gate has the truth table where output is 1 only when inputs differ?

A) XOR

B) XNOR

C) NOR

D) AND

✅ Answer: A) XOR

5. What is the Boolean expression for a NAND gate?

A) A + B

B) A · B

C) (A · B)'

D) (A + B)'

✅ Answer: C) (A · B)'

6. The symbol with a curved back and one input is for which gate?

A) NOT

B) AND

C) OR

D) XOR

✅ Answer: A) NOT

7. Which logic gate gives a HIGH output only when both inputs are LOW?

A) NOR

B) NAND

C) AND

D) OR

✅ Answer: A) NOR

8. The truth table of XNOR gate gives output 1 when:

A) Inputs are different

B) Both inputs are 1

C) Both inputs are 0

D) Inputs are the same

✅ Answer: D) Inputs are the same

9. Which gate has the output expression Y = (A + B)'?

A) NAND

B) NOR

C) AND

D) OR

✅ Answer: B) NOR

10. Which of the following are Universal Gates?

A) AND and OR

B) XOR and XNOR

C) NAND and NOR

D) NOT and AND

✅ Answer: C) NAND and NOR

---

🧮 Logic Circuit Realization – Using Universal Gates

11. Which gate can be used to construct all other gates?

A) AND

B) OR

C) NAND

D) XOR

✅ Answer: C) NAND

12. How many NAND gates are required to construct a NOT gate?

A) 1

B) 2

C) 3

D) 4

✅ Answer: A) 1

13. Using NOR gates, how do you create an OR gate?

A) 2 NOR gates

B) 3 NOR gates

C) 4 NOR gates

D) Not possible

✅ Answer: B) 3 NOR gates

14. Which combination gives AND gate using NAND gates?

A) Invert inputs, then NAND

B) NAND output, then invert

C) NAND output twice

D) NOR of inputs

✅ Answer: B) NAND output, then invert

15. To create an AND gate using only NOR gates, you need:

A) 2 gates

B) 3 gates

C) 4 gates

D) 1 gate

✅ Answer: C) 4 gates

16. Which gate’s output is 0 only when both inputs are 1?

A) OR

B) XOR

C) NAND

D) AND

✅ Answer: C) NAND

17. What is the implementation of A + B using NAND gates?

A) Invert A and B, then NAND

B) A NAND B

C) NAND followed by NOR

D) Cannot be done

✅ Answer: A) Invert A and B, then NAND

18. Which logic gate is used in parity checkers?

A) AND

B) OR

C) XOR

D) NOR

✅ Answer: C) XOR

19. XNOR gate is also called:

A) Even parity gate

B) Difference gate

C) NOT gate

D) Zero detector

✅ Answer: A) Even parity gate

20. The output of a NOR gate is 1 when:

A) Any one input is 1

B) B

oth inputs are 1

C) Both inputs are 0

D) One input is 0

✅ Answer: C) Both inputs are 0

UNIT 3

🔢 Arithmetic Circuits: Adders and Subtractors

1. What are the inputs to a half adder?

A) A, B, Carry-in

B) A, B

C) A, Carry-in

D) A, B, Carry-out

✅ Answer: B) A, B

2. The sum output of a half adder is:

A) A AND B

B) A OR B

C) A XOR B

D) A XNOR B

✅ Answer: C) A XOR B

3. Which of the following is used in a full adder but not in a half adder?

A) AND gate

B) XOR gate

C) Carry-in

D) OR gate

✅ Answer: C) Carry-in

4. How many inputs and outputs does a full adder have?

A) 2 inputs, 1 output

B) 3 inputs, 2 outputs

C) 2 inputs, 2 outputs

D) 3 inputs, 1 output

✅ Answer: B) 3 inputs, 2 outputs

5. The carry output of a full adder is:

A) A XOR B

B) A AND B

C) AB + BC + AC

D) A OR B

✅ Answer: C) AB + BC + AC

6. The difference output of a half subtractor is:

A) A XOR B

B) A AND B

C) A OR B

D) A NAND B

✅ Answer: A) A XOR B

7. Which component is required to design a full subtractor?

A) 1 half subtractor and 1 OR gate

B) 2 half subtractors and 1 OR gate

C) 2 half adders and 1 AND gate

D) 2 full adders

✅ Answer: B) 2 half subtractors and 1 OR gate

8. The borrow output in a half subtractor is:

A) A AND B

B) A' AND B

C) A XOR B

D) A OR B

✅ Answer: B) A' AND B

---

💾 Data Processing Circuits: Encoder, Decoder, MUX, DEMUX

9. How many output lines does a 4-to-2 encoder have?

A) 2

B) 4

C) 3

D) 1

✅ Answer: A) 2

10. The number of output lines in an 8-to-3 encoder is:

A) 2

B) 3

C) 4

D) 8

✅ Answer: B) 3

11. What is the function of an encoder?

A) Decodes input data

B) Generates sum and carry

C) Converts input to binary code

D) Multiplies input signals

✅ Answer: C) Converts input to binary code

12. Which logic circuit converts binary data from n input lines to a maximum of 2ⁿ output lines?

A) Encoder

B) Decoder

C) Multiplexer

D) Comparator

✅ Answer: B) Decoder

13. How many output lines does a 3-to-8 decoder have?

A) 3

B) 8

C) 6

D) 4

✅ Answer: B) 8

14. A 2-to-4 decoder has how many input and output lines?

A) 2 inputs, 4 outputs

B) 4 inputs, 2 outputs

C) 2 inputs, 2 outputs

D) 4 inputs, 4 outputs

✅ Answer: A) 2 inputs, 4 outputs

15. Which circuit has multiple input lines and selects one line to pass to the output?

A) Decoder

B) Encoder

C) Multiplexer

D) Demultiplexer

✅ Answer: C) Multiplexer

16. How many select lines are needed for a 4-to-1 multiplexer?

A) 1

B) 2

C) 3

D) 4

✅ Answer: B) 2

17. What is the function of a demultiplexer?

A) Combines data lines

B) Selects input lines

C) Routes one input to multiple outputs

D) Generates binary numbers

✅ Answer: C) Routes one input to multiple outputs

18. A 1-to-4 demultiplexer requires how many select lines?

A) 1

B) 2

C) 3

D) 4

✅ Answer: B) 2

---

✅ Parity Generator and Checker

19. A 3-bit even parity generator produces output 1 when:

A) Number of 1s is even

B) Number of 1s is odd

C) All bits are 0

D) All bits are 1

✅ Answer: B) Number of 1s is odd

20. The parity checker is

 used to:

A) Detect errors

B) Count 1s

C) Convert binary to decimal

D) Add bits

✅ Answer: A) Detect errors

UNIT 4

🔄 Flip-Flops and Latches

1. Which gate is used in basic SR Latch construction?

A) XOR

B) NAND

C) XNOR

D) AND

✅ Answer: B) NAND

2. A latch is a:

A) Combinational circuit

B) Sequential circuit without clock

C) Clocked sequential circuit

D) Multiplexer

✅ Answer: B) Sequential circuit without clock

3. What is the output of an SR latch when S = 0 and R = 0 (NAND-based)?

A) Invalid

B) No change

C) Reset

D) Set

✅ Answer: B) No change

4. In NOR-based SR latch, which input combination leads to invalid state?

A) S=1, R=1

B) S=0, R=0

C) S=1, R=0

D) S=0, R=1

✅ Answer: A) S=1, R=1

5. Which flip-flop stores one bit of data and has a clock input?

A) SR

B) D

C) T

D) All of these

✅ Answer: D) All of these

6. What is the purpose of the ‘Clock’ in a flip-flop?

A) Provide delay

B) Synchronize operations

C) Invert output

D) Store data

✅ Answer: B) Synchronize operations

7. Which of the following is not a type of triggering?

A) Level triggering

B) Pulse triggering

C) Edge triggering

D) Voltage triggering

✅ Answer: D) Voltage triggering

8. The output of a D flip-flop is:

A) Same as input

B) Always 0

C) Always 1

D) Inverted input

✅ Answer: A) Same as input

9. The JK flip-flop avoids the invalid state of which other flip-flop?

A) D

B) SR

C) T

D) Master-slave

✅ Answer: B) SR

10. When both J and K are high in a JK flip-flop, the output will:

A) Toggle

B) Set

C) Reset

D) No change

✅ Answer: A) Toggle

---

⏱️ More on Flip-Flops and Applications

11. T flip-flop is derived from which flip-flop?

A) JK

B) SR

C) D

D) Master-slave

✅ Answer: A) JK

12. Which flip-flop is commonly used in counters?

A) D flip-flop

B) T flip-flop

C) SR flip-flop

D) Clocked SR

✅ Answer: B) T flip-flop

13. Which flip-flop uses two clocked JK flip-flops to eliminate race condition?

A) D flip-flop

B) T flip-flop

C) Master-Slave JK

D) SR flip-flop

✅ Answer: C) Master-Slave JK

14. What is the purpose of PRESET and CLEAR in flip-flops?

A) Delay outputs

B) Eliminate race condition

C) Initialize or reset outputs

D) Increase speed

✅ Answer: C) Initialize or reset outputs

15. Flip-flops are mainly used in:

A) Memory devices

B) Adders

C) Encoders

D) Decoders

✅ Answer: A) Memory devices

---

🔢 Counters

16. What is a counter?

A) Logic adder

B) Memory cell

C) Sequential circuit that counts pulses

D) Encoder

✅ Answer: C) Sequential circuit that counts pulses

17. Asynchronous counter is also known as:

A) Parallel counter

B) Serial counter

C) Ripple counter

D) Decade counter

✅ Answer: C) Ripple counter

18. What is the major drawback of asynchronous counters?

A) High power

B) Limited speed

C) Propagation delay

D) High cost

✅ Answer: C) Propagation delay

19. Which counter has all flip-flops triggered by the same clock?

A) Ripple counter

B) Serial counter

C) Synchronous counter

D) Decade counter

✅ Answer: C) Synchronous counter

20. A decade counter counts from:

A) 0 to 9

B) 0 to 10

C) 0 to 15

D) 1 to 10

✅ Answer: A) 0 to 9

UNIT 5

🔁 Shift Registers

1. What is the primary function of a shift register?

A) Perform arithmetic operations

B) Store and transfer data

C) Decode binary values

D) Generate clock pulses

✅ Answer: B) Store and transfer data

2. In a Serial In Serial Out (SISO) shift register, data is:

A) Entered and removed in parallel

B) Entered in serial, read in parallel

C) Entered and read in serial

D) Stored permanently

✅ Answer: C) Entered and read in serial

3. Which shift register allows loading all bits at the same time and outputs them one by one?

A) Serial In Serial Out

B) Serial In Parallel Out

C) Parallel In Serial Out

D) Parallel In Parallel Out

✅ Answer: C) Parallel In Serial Out

4. Which shift register outputs all bits simultaneously after shifting in serial data?

A) SISO

B) PISO

C) SIPO

D) PIPO

✅ Answer: C) SIPO

5. Which shift register has both parallel input and parallel output?

A) SIPO

B) PIPO

C) SISO

D) PISO

✅ Answer: B) PIPO

6. A 4-bit shift register can hold:

A) 2 bits

B) 4 bits

C) 8 bits

D) 1 byte

✅ Answer: B) 4 bits

7. Which of the following is not an application of shift registers?

A) Serial-to-parallel conversion

B) Parallel-to-serial conversion

C) Data storage

D) Multiplication

✅ Answer: D) Multiplication

8. Shift registers operate based on:

A) Combinational logic

B) Counters

C) Clock pulses

D) Cache memory

✅ Answer: C) Clock pulses

---

💾 Memory – ROM and Types

9. ROM stands for:

A) Read On Memory

B) Random Only Memory

C) Read Only Memory

D) Rapid Output Memory

✅ Answer: C) Read Only Memory

10. Which type of ROM can be programmed once by the user?

A) PROM

B) EPROM

C) EEPROM

D) Flash

✅ Answer: A) PROM

11. Which ROM type can be erased using UV light?

A) PROM

B) EPROM

C) EEPROM

D) Flash

✅ Answer: B) EPROM

12. EEPROM can be erased using:

A) Ultraviolet light

B) Heat

C) Electrical signals

D) Magnetic field

✅ Answer: C) Electrical signals

13. Which ROM type is commonly used in USB drives and memory cards?

A) EEPROM

B) Flash

C) EPROM

D) PROM

✅ Answer: B) Flash

14. ROM is generally used for:

A) Temporary storage

B) Storing boot programs

C) Arithmetic operations

D) Cache memory

✅ Answer: B) Storing boot programs

---

🧠 Memory – RAM, Cache, and Comparison

15. What does RAM stand for?

A) Read and Memory

B) Random Access Memory

C) Rapid Access Module

D) Registered Arithmetic Memory

✅ Answer: B) Random Access Memory

16. Which type of RAM uses flip-flops to store data?

A) DRAM

B) Flash

C) SRAM

D) EEPROM

✅ Answer: C) SRAM

17. DRAM stores data using:

A) Flip-flops

B) Capacitors

C) Latches

D) Registers

✅ Answer: B) Capacitors

18. Which of the following is faster but more expensive?

A) DRAM

B) SRAM

C) ROM

D) PROM

✅ Answer: B) SRAM

19. Which of the following best compares RAM and ROM?

A) RAM is permanent, ROM is volatile

B) RAM is faster, ROM is slower

C) RAM stores firmware, ROM stores data

D) ROM loses data when power is off

✅ Answer: B) RAM is faster, ROM is slower

20. Cache memory is used to:

A) Store BIOS

B) Backup hard disk

C) Provide faster access to frequently used data

D) Stor

e output permanently

✅ Answer: C) Provide faster access to frequently used data