Logic Gates MCQ Quiz - Objective Question with Answer for Logic Gates - Download Free PDF

Learning about Logic Gates is made much simpler with Logic Gates MCQs. Covering basic gate types like AND, OR, NOT, NAND, and NOR, to more complex topics like gate combinations and Boolean algebra, Logic Gates MCQs offer a comprehensive learning tool. Regular practice with Logic Gates MCQs will solidify your knowledge in this essential area of digital electronics.

Latest Logic Gates MCQ Objective Questions

Logic Gates Question 1:

From the given arrangement, find Q.

1. A + B
2. A + B̅
3. \(\overline + \overline\)
4. More than one of the above
5. None of the above

Answer (Detailed Solution Below)

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Logic Gates Question 1 Detailed Solution

The correct answer is (option 3) i.e. \(\overline + \overline\)

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.

Fig shown below the symbol of AND Gate,

OR Gate: An OR gate is a logic gate having two or more inputs and a single output.

An OR gate operates on logical summation rules.

Fig shown below the symbol of OR Gate,

NOT Gate: A NOT gate is a logic gate that inverts the digital input signal.

It is referred to as an inverter.

Fig shown below the symbol of NOT Gate,

Given logic gate,

It can be simplified as,

Logic Gates Question 2:

1. NOR and NAND gates
2. OR and NOR gates
3. AND and NAND gates
4. More than one of the above
5. None of the above

Answer (Detailed Solution Below)

Logic Gates Question 2 Detailed Solution

The correct answer is option 1):( NOR and NAND gates )

Concept:

• A Universal Gate is a gate by which every other gate can be realized.
• AND, OR, NOT, etc. are basic gates.
• NAND, NOR, etc. are the universal gate
• NOT, AND and OR gate realization using NAND gate is as shown:

Logic Gates Question 3:

1. OR
2. NOR
3. XOR
4. More than one of the above
5. None of the above

Answer (Detailed Solution Below)

Logic Gates Question 3 Detailed Solution

• It is a digital circuit having two or more inputs but only one output.
• It gives a high output if either input A or B or both are low (0) otherwise it gives a high output (1) .
• It is described by the Boolean expression: \(\overline = Q\)
• The above logic gate is the N OR gate .

The truth table for NOR gate:

Logic Gates Question 4:

1. A’B + AB’
2. A’B’ + A’B
3. A’B’ + AB
4. More than one of the above
5. None of the above

Answer (Detailed Solution Below)

Logic Gates Question 4 Detailed Solution

From the truth table, the output is one when both A and B are equal logic.

The Boolean equation of output can be written as:

Output = A B + A̅ B̅

Output Equation: Y = A ⨀ B

1) If B is always Low, the output is the inverted value of the other input A, i.e. A̅.

2) The output is low when both the inputs are different.

3) The output is high when both the inputs are the same.

4) XNOR gate produces an output only when the two inputs are the same.

Logic Gates Question 5:

1. AND or OR
2. NAND or NOR
3. NOT, NOR, NAND
4. More than one of the above
5. None of the above

Answer (Detailed Solution Below)

Logic Gates Question 5 Detailed Solution

Classification of Logic Gates

Classification

Logic Gate

All the other gates can be formed using the NAND or NOR gates.

Hence, NAND and NOR gates are known as universal gates.

The number of NAND and NOR gates required for the formation of other gates are as follows:

GATE

NAND

NOR

Top Logic Gates MCQ Objective Questions

Logic Gates Question 6

The output of the logic gate in figure is

Answer (Detailed Solution Below)

Logic Gates Question 6 Detailed Solution

1) If B is always Low, the output is the inverted value of the other input A, i.e. A̅.

2) The output is low when both the inputs are different.

3) The output is high when both the inputs are the same.

4) XNOR gate produces an output only when the two inputs are same.

Analysis:

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Logic Gates Question 7

The output of logic circuit given below represents _______ gate.

Answer (Detailed Solution Below)

Logic Gates Question 7 Detailed Solution

Output expression Q is equivalent to NAND gate.

Important Points

Output Equation: \(Y = \overline = \overline A + \overline B\)

1) If A is always High, the output is the inverted value of the other input B, i.e. B̅

2) The output is low only when both the inputs are high

3) It is a universal gate

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Logic Gates Question 8

Answer (Detailed Solution Below)

Logic Gates Question 8 Detailed Solution

The number of 2-input NAND gates required to implement a 2-input XOR gate is 4.

Similarly, the number of 2-input NOR gates required to implement a 2-input XNOR gate is 4.

Min. number of NOR Gate

Min. number of NAND Gate

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Logic Gates Question 9

The output Y of the logic circuit given below is:-

Answer (Detailed Solution Below)

Logic Gates Question 9 Detailed Solution

1) If B is always High, the output is the inverted value of the other input A, i.e. A̅.

1) The output is low when both the inputs are the same.

2) The output is high when both the inputs are different.

Explanation:

\(Y = XX+\bar X \bar X\)

Y = 1

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Logic Gates Question 10

What will be the fundamental frequency for the following circuit if each inverter delay is 100 nsec?

1. 1 GHz
2. 0.5 GHz
3. 3.34 MHz
4. 1.67 MHz

Answer (Detailed Solution Below)

Logic Gates Question 10 Detailed Solution

Concept:

The propagation delay, or gate delay, is the length of time that starts when the input to a logic gate becomes stable and valid to change, to the time that the output of that logic gate is stable and valid to change.

Here 2 is multiplied with the propagation delay when logic gates are connected in feedback.

T is the time period of the output

n is the number of logic gates

T pd is the propagation delay of one gate

n = 3 as there are three gates with feedback

Fundamental Frequency is given by f

f = 1.67 MHz

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Logic Gates Question 11

Which of the following logical operations could be computed by the given network?

1. C = AB
2. C = A + B
3. \(C = \overline \)
4. \(C = \overline \)

Answer (Detailed Solution Below)

Logic Gates Question 11 Detailed Solution

Concept:

In Digital Electronics, Logic 1 means High and Logic 0 means low.

Whenever in diode, if 1 is applied to anode and 0 to cathode then Diode acts as a short circuit i.e. ON.

And if 0 is applied to anode and 1 to cathode Diode acts as open circuit i.e. OFF.

Explanation:

The given logic circuit is

For different logic of A and B,4 cases are there and according to that logic of C will vary.

Case 1

When A is logic 0 and B is logic 0

Then the logic of C will be 0.

Case 2

When A is logic 0 and B is logic 1

Then the logic of C will be 1.

Case 3

When A is logic 1 and B is logic 0

Then the logic of C will be 1.

Case 4

When A is logic 1 and B is logic 1

Then the logic of C will be 1.

According to Result, we make a table