TOP 100+ MCQs On Logic Gates with Answers with FREE PDF

Everybody knows about the superlative importance of logical gates in digital electronics system design. We are presenting MCQs on logic gates with answers. Now, even if you have done a course on digital electronics system design, you should still try these questions to test your knowledge and to see how well you absorb teaching from school or college.

MCQs On Logic Gates with Answers

1. The AND function can be used to ________ and the OR function can be used to ________ .

A. enable, disable

B. disable, enable

C. enable or disable, enable or disable

D. detect, invert

Answer: Option C

2. One advantage TTL has over CMOS is that TTL is ________.

A. less expensive

B. not sensitive to electrostatic discharge

C. faster

D. more widely available

Answer: Option B

3. A 2-input NOR gate is equivalent to a ________.

A. negative-OR gate

B. negative-AND gate

C. negative-NAND gate

D. none of the above

Answer: Option B

4. If a 3-input OR 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 C

5. Fan-out is specified in terms of ________.

A. voltage

B. current

C. wattage

D. unit loads

Answer: Option D

6. The output of an AND gate with three inputs, A, B, and C, is HIGH when ________.

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

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

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

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

Answer: Option C

7. If a 3-input NOR 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

8. If a signal passing through a gate is inhibited by sending a LOW into one of the inputs, and the output is HIGH, the gate is a(n):





Answer: Option B

9. A device used to display one or more digital signals so that they can be compared to expected timing diagrams for the signals is a:


B. spectrum analyzer

C. logic analyzer

D. frequency counter

Answer: Option C

10. When used with an IC, what does the term “QUAD” indicate?

A. 2 circuits

B. 4 circuits

C. 6 circuits

D. 8 circuits

Answer: Option B

11. How many input combinations would a truth table have for a six-input AND gate?

A. 32

B. 48

C. 64

D. 128

Answer: Option C

12. What is the circuit number of the IC that contains four two-input AND gates in standard TTL?

A. 7402

B. 7404

C. 7408

D. 7432

Answer: Option C

13. The terms “low speed” and “high speed,” applied to logic circuits, refer to the ________.

A. rise time

B. fall time

C. propagation delay time

D. clock speed

Answer: Option C

14. The NOR logic gate is the same as the operation of the ________ gate with an inverter connected to the output.




D. none of the above

Answer: Option A

15. With regard to an AND gate, which statement is true?

A. An AND gate has two inputs and one output.

B. An AND gate has two or more inputs and two outputs.

C. If one input to a 2-input AND gate is HIGH, the output reflects the other input.

D. A 2-input AND gate has eight input possibilities.

Answer: Option C

16. The term “hex inverter” refers to:

A. an inverter that has six inputs

B. six inverters in a single package

C. a six-input symbolic logic device

D. an inverter that has a history of failure

Answer: Option B

17. How many inputs are on the logic gates of a 74HC21 IC?

A. 1

B. 2

C. 3

D. 4

Answer: Option D

18. The basic logic gate whose output is the complement of the input is the:

A. OR gate

B. AND gate

C. inverter

D. comparator

Answer: Option C

19. When reading a Boolean expression, what does the word “NOT” indicate?

A. the same as

B. inversion

C. high

D. low

Answer: Option B

20. The output of an exclusive-NOR gate is HIGH if ________.

A. the inputs are equal

B. one input is HIGH, and the other input is LOW

C. the inputs are unequal

D. none of the above

Answer: Option A

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