Objective Questions on Logic Gate

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Objective Questions on Logic Gate

Objective Questions on Logic Gate, digital logic gate questions, MCQ on logic gate, digital logic design multiple-choice questions, Engineering MCQ, Multiple Choice Question based on Engineering, Digital Electronics MCQ, AND Gate MCQ, OR Gate MCQ, NAND Gate MCQ, Objective Questions on Logic Gate

MULTIPLE CHOICE QUESTIONS

Q.1. If A, B and C are the inputs of AND gate, then the output Y is HIGH for

  • A = 1, B = 1, C = 0
  • A = 0, B = 0, C = 0
  • A = 1, B = 1, C = 1
  • A = 1, B = 0, C = 1

Answer: A = 1, B = 1, C = 1

Q.2. NAND gate is

  • AND followed by NOT
  • NOT followed by AND
  • Two AND gates interconnected
  • OR followed by AND

Answer: AND followed by NOT

Q.3. If one of the inputs of the 2-input logic gate is LOW, then which of the following gate still has a HIGH output is HIGH?

  • AND
  • NAND
  • NOR
  • OR

Answer: NAND

Q.4. The Boolean expression for a 3-input AND gate is

  • Y = AB + BC + CA
  • Y = ABC
  • Y = A + B + C
  • Y = AB + C

Answer: Y = ABC

Q.5. Which of the following logical operations has ‘+’ as its symbol?

  • AND
  • NAND
  • OR
  • NOT

Answer: OR

Q.6. The logic expression for a NOR gate is given as

  • X=\bar{A}+B
  • X=A+\bar{B}
  • X=A+B
  • X=\bar{A+B}

Answer: X=\bar{A+B}

Q.7. The Boolean expression for the output of a NOR gate is similar to a

  • NAND gate followed by an inverter
  • OR gate followed by an inverter
  • AND gate followed by an inverter
  • NOR gate followed by an inverter

Answer: OR gate followed by an inverter

Q.8. A NOT gate has a HIGH output when

  • The input is LOW
  • The input is HIGH
  • Power supply is ON
  • Power supply is OFF

Answer: The input is LOW

Q.9. An exclusive-OR gate has a HIGH output when

  • All inputs are LOW
  • All inputs are HIGH
  • The inputs have opposite logic
  • None of the above

Answer: The inputs have opposite logic

Q.10. Which of the following gates are interchangeable?

  • NAND and NOR
  • NOR and OR
  • AND and OR
  • NOR and bubbled OR

Answer: NAND and NOR

Q.11. A 2-input NOR gate is equivalent to a

  • Negative-OR gate
  • Negative-AND gate
  • Negative-NAND gate
  • None of the above

Answer: Negative-AND gate

Q.12. The output ‘Y’ of the given logic diagram is

Objective Questions on Logic Gate
  • Y = (A + B) C
  • Y = AB + C
  • Y = A + B + C
  • Y = A + BC

Answer: Y = (A + B) C

Q.13. The Boolean expression for XNOR is given as

  • A+B
  • A.B
  • A \oplus B
  • \bar{A \oplus B}

Answer: A \oplus B

Q.14. A Combinational circuit can be designed using only

  • AND gates
  • OR gates
  • OR and X-NOR gates
  • NOR gates

Answer: NOR gates

Q.15. How many NOR gates are required to obtain AND operations?

  • 2
  • 3
  • 4
  • 5

Answer: 3

Q.16. A combinational circuit can be designed using only

  • AND gates
  • OR gates
  • OR and X-NOR gates
  • NOR gates

Answer: NOR gates

Q.17. A combinational circuit can be designed using only

  • AND gates
  • OR gates
  • OR and X-NOR gates
  • NAND gates

Answer: NAND gates

Q.18. What is the logic which controls a stair case light associated with two switches A and B located at the bottom and top of the stair case respectively?

  • OR
  • AND
  • X-OR
  • X-NOR

Answer: X-OR

Q.19. The NAND gate can function as a NOT gate if

  • all inputs are connected together
  • inputs are left open
  • one input is set to 0
  • one input is Set to 1

Answer: all inputs are connected together

Q.20. The NOR gate cal, function as a NOT gate if

  • all inputs are connected together
  • inputs are left open
  • one input is set to 0
  • one input is set to 1

Answer: all inputs are connected together

Q.21. An X-OR gate gives a high output

  • if there are odd number of 1 s
  • if it has even number of 0s
  • if the decimal value of digital word even
  • for odd decimal value

Answer: if there are odd number of 1 s

Q.22. An exclusive NOR gate is logically equivalent to

  • inverter followed by an X-OR gate
  • X-OR gate followed by an inverter
  • complement of a NOR gate
  • NOT gate followed by a NOR gate

Answer: X-OR gate followed by an inverter

Q.23. The X-OR and X-NOR gates can have how many inputs?

  • 2
  • 1
  • 4
  • any number

Answer: 2

Q.24. The logic expression AB+\bar{A}\bar{B} can be implemented by giving the inputs A and B to a two-input.

  • NOR gate
  • NAND gate
  • X-OR gate
  • X-NOR gate

Answer: X-NOR gate

Q.25. The logic expression A\bar{B}+\bar{A}B can be implemented by giving inputs A and B to a two-input.

  • NOR gate
  • NAND gate
  • X-OR gate
  • X-NOR gate

Answer: X-OR gate

 Q.26. Which of the following is known as a mod-2 adder?

  • X-OR gate
  • X-NOR gate
  • NAND gate
  • NOR gate

Answer: X-OR gate

Q.27. What is the minimum number of two-input NAND gates used to perform the function of 2-input OR gate?

  • One
  • Two
  • Three
  • Four

Answer: Three

Q.28. NOT gates are to be added to the inputs of which gate to convert it to a NAND gate?

  • OR
  • AND
  • NOT
  • X-OR

Answer: OR

Q.29. NOT gates are to be added to the inputs of which gate to convert it to a NOR gate?

  • OR
  • AND
  • NAND
  • X-NOR

Answer: NAND

Q.30. What logic function is produced by adding inverters to the inputs of an AND gate?

  • OR
  • NOR
  • NAND
  • X-OR

Answer: NOR

Logic Gate MCQ

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