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

A half adder circuit is basically made up of an a AND gate with XOR gate as shown below.

• A half adder is also known as XOR gate because XOR is applied to both inputs to produce the sum
• Half adder can add only two bits (A and B) and has nothing to do with the carry
• If the input to a half adder has a carry, then it will neglect it and adds only the A and B bits
• That means the binary addition process is not complete and that's why it is called a half adder

Sum (S) = A⊕B, Carry = A.B

The Correct Answer is I but not II.

• NAND gate is a functionally complete set of gates.
• In the logic gate, a functionally complete collection of logical connectives or Boolean operators is one which can be used to express all possible truth tables by combining members of the set into a Boolean expression.
• A well-known complete set of connectors is {AND, NOT} and each of the singleton sets {NAND} is functionally complete, consisting of binary conjunction and negation.
• A NAND gate is a logic gate that generates a false output only if all its inputs are valid, so its output is complementary to that of an AND gate.
• A low output only results if all the inputs to the gate are high; a high output results if any input is low.

Key Points

A flip-flop is used to store the binary data.

Flip-Flop:

• A flip-flop is the basic storage element in sequential logic.
• A flip-flop is a device that stores a single bit (binary digit) of data.
• The stored data can be changed by applying varying inputs.
• Flip Flops are edge-triggered while the latch is level-triggered.
• Flip Flops are of 4 types: SR, JK, T, and D flip-flops.

Additional Information 

​Register:

• A Register is a collection of flip-flops.
• For storing n-bit data, a register comprising of n number of flip-flops is used.

Gates:

• A logic gate is a device that acts as a building block for digital circuits.
• They perform basic logical functions that are fundamental to digital circuits. 
• Example: AND, OR, NOT, NAND, NOR, XOR, XNOR

Explanation:

The expression 16log2 3 s is an example of an exponential function where the base is 16 and the exponent is log₂ 3.

The log2 3 part is a logarithm in base 2. The logarithm of a number is the exponent to which the base must be raised to get that number. So, log2 3 means "What power do you need to raise 2 to in order to get 3".

Now, let's simplify the expression. We know that 16 is equal to 2⁴ . So, we can rewrite the expression as (24)^log2 3.

The log2 3 part is still the exponent to which 2 must be raised to get 3. So 4.log₂3 means "what power do you need to raise 2 to in order to get 3, and then multiply that power by 4.

so finally,(24)log2 3 = 3⁴ = 81.

When two switches are connected in parallel, then the circuit acts as an OR gate

The input X is connected to output Y when at least one of the switch A and Switch B is closed.

From the above truth table, the circuit diagram represents an OR gate i.e. (A + B)

When two switches are connected in series, then the circuit acts as an AND gate.

Now, the input X is connected to output Y when both the switch A and Switch B are closed.

From the above truth table, the circuit diagram represents an AND gate i.e. Y = AB

When two switches are connected in parallel, then the circuit acts as an OR gate

The input X is connected to output Y when at least one of the switch A and Switch B is closed.

From the above truth table, the circuit diagram represents an OR gate i.e. (A + B)

When two switches are connected in series, then the circuit acts as an AND gate.

Now, the input X is connected to output Y when both the switch A and Switch B are closed.

From the above truth table, the circuit diagram represents an AND gate i.e. Y = AB

A half adder circuit is basically made up of an a AND gate with XOR gate as shown below.

• A half adder is also known as XOR gate because XOR is applied to both inputs to produce the sum
• Half adder can add only two bits (A and B) and has nothing to do with the carry
• If the input to a half adder has a carry, then it will neglect it and adds only the A and B bits
• That means the binary addition process is not complete and that's why it is called a half adder

Sum (S) = A⊕B, Carry = A.B

The Correct Answer is I but not II.

• NAND gate is a functionally complete set of gates.
• In the logic gate, a functionally complete collection of logical connectives or Boolean operators is one which can be used to express all possible truth tables by combining members of the set into a Boolean expression.
• A well-known complete set of connectors is {AND, NOT} and each of the singleton sets {NAND} is functionally complete, consisting of binary conjunction and negation.
• A NAND gate is a logic gate that generates a false output only if all its inputs are valid, so its output is complementary to that of an AND gate.
• A low output only results if all the inputs to the gate are high; a high output results if any input is low.

Key Points

Explanation:

The expression 16log2 3 s is an example of an exponential function where the base is 16 and the exponent is log₂ 3.

The log2 3 part is a logarithm in base 2. The logarithm of a number is the exponent to which the base must be raised to get that number. So, log2 3 means "What power do you need to raise 2 to in order to get 3".

Now, let's simplify the expression. We know that 16 is equal to 2⁴ . So, we can rewrite the expression as (24)^log2 3.

The log2 3 part is still the exponent to which 2 must be raised to get 3. So 4.log₂3 means "what power do you need to raise 2 to in order to get 3, and then multiply that power by 4.

so finally,(24)log2 3 = 3⁴ = 81.

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.

For Ex - NOT, AND and OR gate realization using NAND gate is as shown:

Explanation:

Let us consider 

x = log_a N

By logarithmic rule we have,

a^x = N

Put the value of x in the above equation

a^log_aN = N

Concept:

OR Gate: The Logic OR Gate is a digital logic circuit whose output is High (1) when any of the input is High

whereas when both inputs are Low (0), output will also be Low.

Here, 

A ,B = inputs , C = Output.

"+" = it denotes OR gate

The Correct Answer is OR Gate.

(7214)₈ = 7 × 8³ + 2 × 82 + 1 × 81 + 4 × 80 = (3724)₁₀

Option 2: 

(EAC)16 = E × 162 + A × 161 + C × 160

(EAC)16 = 14 × 162 + 10 × 161 + 12 × 160 = (3756)10

Therefore (EAC)16 is not equal to (7214)8?

Binary to Octal conversion table:

Binary to Hexadecimal conversion table:

Tips and Tricks:

Every digit in octal represents 3 bits of binary and every digit in hexadecimal is 4 bits in binary

(513)8 = (101 001 011)2

Forming pairs of 4 to get the hexadecimal representation, we get:

(111  010  001  100)2  =  (1110  1000  1100)2 = (14B)16 = (E 8 C)16

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.

Example:

NOT, AND and OR gate realization using NAND gate is as shown:

A flip-flop is used to store the binary data.

Flip-Flop:

• A flip-flop is the basic storage element in sequential logic.
• A flip-flop is a device that stores a single bit (binary digit) of data.
• The stored data can be changed by applying varying inputs.
• Flip Flops are edge-triggered while the latch is level-triggered.
• Flip Flops are of 4 types: SR, JK, T, and D flip-flops.

Additional Information 

​Register:

• A Register is a collection of flip-flops.
• For storing n-bit data, a register comprising of n number of flip-flops is used.

Gates:

• A logic gate is a device that acts as a building block for digital circuits.
• They perform basic logical functions that are fundamental to digital circuits. 
• Example: AND, OR, NOT, NAND, NOR, XOR, XNOR