Explore topic-wise MCQs in Digital Electronics.

This section includes 51 Mcqs, each offering curated multiple-choice questions to sharpen your Digital Electronics knowledge and support exam preparation. Choose a topic below to get started.

1.

Implementation of the Boolean expression results in ________.

A. three AND gates, one OR gate
B. three AND gates, one NOT gate, one OR gate
C. three AND gates, one NOT gate, three OR gates
D. three AND gates, three OR gates
Answer» C. three AND gates, one NOT gate, three OR gates
2.

Before an SOP implementation, the expression would require a total of how many gates?

A. 1
B. 2
C. 4
D. 5
Answer» E.
3.

Assume you have A, B, C, and D available but not their complements. The minimum number of 2-input NAND gates required to implement the equation is ________.

A. 3
B. 4
C. 5
D. 6
Answer» D. 6
4.

How many AND gates are required to implement the Boolean expression, ?

A. 1
B. 2
C. 3
D. 4
Answer» D. 4
5.

How many NOT gates are required to implement the Boolean expression, ?

A. 1
B. 2
C. 4
D. 5
Answer» C. 4
6.

A is defined as ________.

A. a common point in a circuit
B. a circuit implemented as a sum-of-products
C. the output signals from a circuit
D. a shorted input
Answer» B. a circuit implemented as a sum-of-products
7.

The expression can be directly implemented using only ________.

A. an XOR gate
B. an XNOR gate
C. an AOI circuit
D. three 2-input NAND gates
Answer» B. an XNOR gate
8.

To implement the expression , it takes one OR gate and ________.

A. three AND gates and three inverters
B. three AND gates and four inverters
C. three AND gates
D. one AND gate
Answer» B. three AND gates and four inverters
9.

A logic circuit with an output consists of ________.

A. two AND gates, two OR gates, two inverters
B. three AND gates, two OR gates, one inverter
C. two AND gates, one OR gate, two inverters
D. two AND gates, one OR gate
Answer» D. two AND gates, one OR gate
10.

Referring to the GAL diagram, which is the correct logic function?

A. [A].
B. [B].
C. [C].
D. [D].
Answer» B. [B].
11.

One positive pulse with tw = 75 µs is applied to one of the inputs of an exclusive-OR circuit. A second positive pulse with tw = 15 µs is applied to the other input beginning 20 µs after the leading edge of the first pulse. Which statement describes the output in relation to the inputs?

A. The exclusive-OR output is a 20 s pulse followed by a 40 s pulse, with a separation of 15 s between the pulses.
B. The exclusive-OR output is a 20 s pulse followed by a 15 s pulse, with a separation of 40 s between the pulses.
C. The exclusive-OR output is a 15 s pulse followed by a 40 s pulse.
D. *The exclusive-OR output is a 20 s pulse followed by a 15 s pulse, followed by a 40 s pulse.
Answer» E.
12.

One possible output expression for an AND-OR-Invert circuit having one AND gate with inputs A, B, and C and one AND gate with inputs D and E is ________.

A. [A].
B. [B].
C. [C].
D. [D].
Answer» D. [D].
13.

The Boolean SOP expression obtained from the truth table below is ________.

A. [A].
B. [B].
C. [C].
D. None of these
Answer» D. None of these
14.

The 8-input XOR circuit shown has an output of Y = 1. Which input combination below (ordered A – H) is correct?

A. 10111100
B. 10111000
C. 11100111
D. 00011101
Answer» B. 10111000
15.

A 4-variable AND-OR-Invert circuit produces a 0 at its Y output. Which combination of inputs is correct?

A. [A].
B. [B].
C. [C].
D. none of the above
Answer» D. none of the above
16.

A node is defined as ________.

A. a common point in a circuit
B. a circuit implemented as a sum-of-products
C. the output signals from a circuit
D. a shorted input
Answer» B. a circuit implemented as a sum-of-products
17.

The output of an AND gate is HIGH when any input is HIGH.

A. 1
B.
Answer» C.
18.

Assume that you have a 3-input NAND gate but need only a 2-input gate. The unused input should be ________.

A. connected to ground
B. left open
C. connected to a HIGH
D. any of the above
Answer» D. any of the above
19.

Using the universal property of a NAND gate, one or more NAND gates can be used to replace an ________.

A. OR gate
B. AND gate
C. inverter
D. any of the above
Answer» E.
20.

An exclusive-OR gate's output is HIGH when its inputs are equal.

A. 1
B.
Answer» C.
21.

A NOR gate's truth table is the opposite of that of an OR gate.

A. 1
B.
Answer» B.
22.

A VHDL component is a predefined logic function.

A. 1
B.
Answer» C.
23.

The inverter can be produced with how many NAND gates?

A. 1
B. 2
C. 3
D. 4
Answer» B. 2
24.

The symbol shown represents a(n) ________.

A. AND gate
B. OR gate
C. NAND gate
D. NOR gate
Answer» E.
25.

When the output of an AND-OR circuit is complemented, it results in an AND-OR-Invert circuit.

A. 1
B.
Answer» B.
26.

The expression can be directly implemented using only ________.

A. an XOR gate
B. an XNOR gate
C. an AOI circuit
D. three 2-input NAND gates
Answer» D. three 2-input NAND gates
27.

A NAND gate can function as a negative-OR gate.

A. 1
B.
Answer» B.
28.

If both inputs of a 2-input NOR gate are connected, the gate will function as an ________.

A. OR gate
B. AND gate
C. inverter
D. any of the above
Answer» D. any of the above
29.

How many NOT gates are required to implement the Boolean expression, ?

A. 1
B. 2
C. 4
D. 5
Answer» C. 4
30.

The symbol shown represents ________.

A. AND-OR logic
B. AOI logic
C. XOR gate
D. XNOR gate
Answer» B. AOI logic
31.

A 4-variable AND-OR circuit produces a 1 at its Y output. Which combination of inputs is correct?

A. A = 0, B = 0, C = 0, D = 0
B. A = 0, B = 1, C = 1, D = 0
C. A = 1, B = 1, C = 0, D = 0
D. A = 1, B = 0, C = 0, D = 0
Answer» D. A = 1, B = 0, C = 0, D = 0
32.

Implementing the expression using NAND logic, we get:

A. (A)
B. (B)
C. (C)
D. (D)
Answer» C. (C)
33.

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

A. 1
B.
Answer» B.
34.

An AND gate is a universal gate.

A. 1
B.
Answer» C.
35.

A NOR gate is a universal gate.

A. 1
B.
C. 1
D.
Answer» B.
36.

A logic circuit with an output consists of ________.

A. two AND gates, two OR gates, two inverters
B. three AND gates, two OR gates, one inverter
C. two AND gates, one OR gate, two inverters
D. two AND gates, one OR gate
Answer» D. two AND gates, one OR gate
37.

The following waveform pattern is for a(n) ________.

A. 2-input AND gate
B. 2-input OR gate
C. Exclusive-OR gate
D. None of the above
Answer» C. Exclusive-OR gate
38.

One positive pulse with tw = 75 µs is applied to one of the inputs of an exclusive-OR circuit. A second positive pulse with tw = 15 µs is applied to the other input beginning 20 µs after the leading edge of the first pulse. Which statement describes the output in relation to the inputs?

A. The exclusive-OR output is a 20 s pulse followed by a 40 s pulse, with a separation of 15 s between the pulses.
B. The exclusive-OR output is a 20 s pulse followed by a 15 s pulse, with a separation of 40 s between the pulses.
C. The exclusive-OR output is a 15 s pulse followed by a 40 s pulse.
D. *The exclusive-OR output is a 20 s pulse followed by a 15 s pulse, followed by a 40 s pulse.
Answer» E.
39.

How many AND gates are required to implement the Boolean expression, ?

A. 1
B. 2
C. 3
D. 4
Answer» D. 4
40.

How many 2-input NOR gates does it take to produce a 2-input NAND gate?

A. 1
B. 2
C. 3
D. 4
Answer» E.
41.

Implementing the expression with NOR logic, we get:

A. (A)
B. (B)
C. (C)
D. (D)
Answer» B. (B)
42.

A gate can drive a number of load gate inputs up to its specified ________.

A. supply voltage
B. noise margin
C. fan-in
D. fan-out
Answer» E.
43.

Before an SOP implementation, the expression would require a total of how many gates?

A. 1
B. 2
C. 4
D. 5
Answer» E.
44.

Implementation of the Boolean expression results in ________.

A. three AND gates, one OR gate
B. three AND gates, one NOT gate, one OR gate
C. three AND gates, one NOT gate, three OR gates
D. three AND gates, three OR gates
Answer» C. three AND gates, one NOT gate, three OR gates
45.

Assume you have A, B, C, and D available but not their complements. The minimum number of 2-input NAND gates required to implement the equation is ________.

A. 3
B. 4
C. 5
D. 6
Answer» D. 6
46.

A 4-variable AND-OR circuit produces a 0 at its Y output. Which combination of inputs is correct?

A. A = 0, B = 0, C = 1, D = 1
B. A = 1, B = 1, C = 0, D = 0
C. A = 1, B = 1, C = 1, D = 1
D. A = 1, B = 0, C = 1, D = 0
Answer» E.
47.

Implementing the expression AB + CDE using NAND logic, we get:

A. (A)
B. (B)
C. (C)
D. (D)
Answer» B. (B)
48.

The output of an exclusive-NOR gate is 1. Which input combination is correct?

A. A = 1, B = 0
B. A = 0, B = 1
C. A = 0, B = 0
D. none of the above
Answer» D. none of the above
49.

To implement the expression , it takes one OR gate and ________.

A. three AND gates and three inverters
B. three AND gates and four inverters
C. three AND gates
D. one AND gate
Answer» B. three AND gates and four inverters
50.

The output of a NAND gate is LOW when all inputs are HIGH at the same time.

A. 1
B.
C. 1
D.
Answer» B.