TOP 100+ Logic Gate Question and Answers with FREE PDF

Logic Gate Question and Answers for basic concepts: Are you a beginner in electronics devices? If your answer is a YES, then it’s better to first learn the basic fundamentals of these devices. These Logic Gate Question and Answers will help you a lot in doing so.  The article comprises numerous self-explanatory questions with answers which are simple and easy to understand. Let’s explore some important terminologies of Logic Gate:

Logic Gate: Logic gates are primarily implemented using diodes or transistors acting as electronic switches, but can also be constructed using vacuum tubes, electromagnetic relays (relay logic), fluidic logic, pneumatic logic, optics, molecules, or even mechanical elements. With amplification, logic gates can be cascaded in the same way that Boolean functions can be composed, allowing the construction of a physical model of all of the Boolean logic, and therefore, all of the algorithms and mathematics that can be described with Boolean logic.

XOR Gate: XOR gate is a digital logic gate that gives a true output when the number of true inputs is odd. An XOR gate implements an exclusive or from mathematical logic; that is, true output results if one, and only one, of the inputs to the gate is true. If both inputs are false or both are true, false output results.

AND Gate: An AND gate is a logic gate having two or more inputs and a single output. An AND gate operates on logical multiplication rules. The output of the AND gate is true only if all the inputs are true, otherwise, it will be false.

NAND Gate: The NAND gate is the most fundamental digital logic circuit. It is referred to as “universal” because it can be used to implement any other type of logic gate by using only a combination of NAND gates. The NAND gate is a very important device because it can also be used as a universal building block for combinational and sequential logic circuits.

NOR Gate: NOR Gate is a digital logic gate that implements logical NOR – it behaves according to the truth table to the right. A HIGH output (1) results if both the inputs to the gate are LOW (0); if one or both input is HIGH (1), a LOW output (0) results. NOR is the result of the negation of the OR operator. It can also be seen as an AND gate with all the inputs inverted.

Logic Gate Question and Answers

1. Output will be a LOW for any case when one or more inputs are zero for a(n):

A. OR gate

B. NOT gate

C. AND gate

D. NOR gate

Answer: Option C

2. How many pins does the 4049 IC have?

A. 14

B. 16

C. 18

D. 20

Answer: Option B

4. Which of the following choices meets the minimum requirement needed to create specialized waveforms that are used in digital control and sequencing circuits?

A. basic gates, a clock oscillator, and a repetitive waveform generator

B. basic gates, a clock oscillator, and a Johnson shift counter

C. basic gates, a clock oscillator, and a DeMorgan pulse generator

D. basic gates, a clock oscillator, a repetitive waveform generator, and a Johnson shift counter

Answer: Option A

4. The output of an OR gate with three inputs, A, B, and C, is LOW when ________.

A. A = 0, B = 0, C = 0

B. A = 0, B = 0, C = 1

C. A = 0, B = 1, C = 1

D. all of the above

Answer: Option A

5. Which of the following logical operations is represented by the + sign in Boolean algebra?

A. inversion



D. complementation

Answer: Option C

6. TTL operates from a ________.

A. 9-volt supply

B. 3-volt supply

C. 12-volt supply

D. 5-volt supply

Answer: Option D

7. The output of a NOR gate is HIGH if ________.

A. all inputs are HIGH

B. any input is HIGH

C. any input is LOW

D. all inputs are LOW

Answer: Option D

8. The switching speed of CMOS is now ________.

A. competitive with TTL

B. three times that of TTL

C. slower than TTL

D. twice that of TTL

Answer: Option A

9. The format used to present the logic output for the various combinations of logic inputs to a gate is called a(n):

A. Boolean constant

B. Boolean variable

C. truth table

D. input logic function

Answer: Option C

10. The power dissipation, PD, of a logic gate is the product of the ________.

A. dc supply voltage and the peak current

B. dc supply voltage and the average supply current

C. ac supply voltage and the peak current

D. ac supply voltage and the average supply current

Answer: Option B

11. How many AND gates are found in a 7411 IC?

A. 1

B. 2

C. 3

D. 4

Answer: Option C

12. Which of the following equations would accurately describe a four-input OR gate when A = 1, B = 1, C = 0, and D = 0?

A. 1 + 1 + 0 + 0 = 01

B. 1 + 1 + 0 + 0 = 1

C. 1 + 1 + 0 + 0 = 0

D. 1 + 1 + 0 + 0 = 00

Answer: Option B

13. What is the name of a digital circuit that produces several repetitive digital waveforms?

A. an inverter

B. an OR gate

C. a Johnson shift counter

D. an AND gate

Answer: Option C

14. The basic types of programmable arrays are made up of ________.

A. AND gates

B. OR gates

C. NAND and NOR gates

D. AND gates and OR gates

Answer: Option D

15. The logic gate that will have HIGH or “1” at its output when any one (or more) of its inputs is HIGH is a(n):

A. OR gate

B. AND gate

C. NOR gate

D. NOT operation

Answer: Option A

16. If a 3-input AND gate has eight input possibilities, how many of those possibilities will result in a HIGH output?

A. 1

B. 2

C. 7

D. 8

Answer: Option A

17. The Boolean expression for a 3-input AND gate is ________.

A. X = AB

B. X = ABC

C. X = A + B + C

D. X = AB + C

Answer: Option B

18. A CMOS IC operating from a 3-volt supply will consume ________.

A. less power than a TTL IC

B. more power than a TTL IC

C. the same power as a TTL IC

D. no power at all

Answer: Option A

19. CMOS IC packages are available in ________.

A. DIP configuration

B. SOIC configuration

C. DIP and SOIC configurations

D. neither DIP nor SOIC configurations

Answer: Option C

20. Which of the following is not a basic Boolean operation?





Answer: Option D

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