Ec230 Logic Circuit Lab Sessional Evaluation
Questions and Answers
- 1.
What does the small bubble on the output of the NAND gate logic symbol mean?
- A.
Open collector output
- B.
Tristate
- C.
The output is inverted.
- D.
None of the above
Correct Answer
C. The output is inverted.Explanation
The small bubble on the output of the NAND gate logic symbol indicates that the output is inverted. In other words, the output will be the opposite of what the input is. If the input is high, the output will be low, and vice versa.Rate this question:
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- 2.
The parameter through which 4 distinct values can be represented is known as ________
- A.
Bit
- B.
Byte
- C.
Nibble
- D.
Word
Correct Answer
C. NibbleExplanation
A nibble is a unit of data that consists of 4 bits, allowing it to represent 16 distinct values (2^4). It is commonly used in computing and digital systems to represent hexadecimal digits, where each digit corresponds to a unique combination of 4 bits. Therefore, a nibble is the parameter through which 4 distinct values can be represented.Rate this question:
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- 3.
For the truth table of given figure Y= ......
- A.
A
- B.
A+B
- C.
A¯+B [ NB: A¯ is A compliment]
- D.
A+B¯ [ NB: B¯ is B compliment]
Correct Answer
D. A+B¯ [ NB: B¯ is B compliment]Explanation
The given truth table represents the output Y based on the inputs A and B. The expression A+B¯ means A OR B compliment, which implies that the output Y will be true if either A or the complement of B is true. This is consistent with the truth table as it shows that Y is true for all combinations of A and B except when both A and B are false. Therefore, A+B¯ is the correct answer.Rate this question:
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- 4.
How many two-input AND and OR gates are required to realize Y = CD+EF+G?
- A.
2, 2
- B.
2, 3
- C.
3, 3
- D.
3, 2
Correct Answer
A. 2, 2Explanation
To realize the expression Y = CD+EF+G, we need two two-input AND gates and two two-input OR gates. Each AND gate is used to combine two inputs (C and D, E and F) and each OR gate is used to combine the outputs of the AND gates and the input G. Therefore, the correct answer is 2, 2.Rate this question:
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- 5.
How many outputs are required for the implementation of a subtractor?
- A.
1
- B.
2
- C.
3
- D.
4
Correct Answer
B. 2Explanation
A subtractor is a digital circuit that performs the operation of subtraction. It takes two inputs, the minuend and the subtrahend, and produces an output which is the difference between the two inputs. Therefore, a subtractor requires two outputs: one for the difference and another for any borrow generated during the subtraction process.Rate this question:
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- 6.
The full subtractor can be implemented using ___________
- A.
Two XOR and an OR gates
- B.
Two half subtractors and an OR gate
- C.
Two multiplexers and an AND gate
- D.
Two comparators and an AND gate
Correct Answer
B. Two half subtractors and an OR gateExplanation
A full subtractor is a combinational circuit that performs subtraction of three input bits: the minuend, subtrahend, and borrow-in. It produces two outputs: the difference and the borrow-out. The two half subtractors are used to subtract the two least significant bits (LSBs) of the minuend and subtrahend, along with the borrow-in. The outputs of the two half subtractors are then combined using an OR gate to obtain the final difference. Therefore, the correct answer is "Two half subtractors and an OR gate."Rate this question:
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- 7.
What is the difference between a 7400 and a 7411 IC?
- A.
7400 has four two-input NAND gates; 7411 has three three-input AND gates
- B.
7400 has two four-input NAND gates; 7411 has three three-input AND gates
- C.
7400 has two four-input AND gates; 7411 has three three-input NAND gates
- D.
7400 has four two-input AND gates; 7411 has three three-input NAND gates
Correct Answer
A. 7400 has four two-input NAND gates; 7411 has three three-input AND gatesExplanation
The difference between a 7400 and a 7411 IC is that the 7400 has four two-input NAND gates, while the 7411 has three three-input AND gates.Rate this question:
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- 8.
Simplify the K-map
- A.
A XOR B
- B.
A compliment
- C.
A XNOR B
- D.
A compliment + B
Correct Answer
C. A XNOR BExplanation
The given expression is A XNOR B, which means that the output is true only when both A and B have the same value (either both true or both false). This can be simplified further by using the complement of A, which is not(A). Therefore, the simplified expression is A' XNOR B.Rate this question:
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- 9.
Simplify the K-map
- A.
A
- B.
A XOR B
- C.
A+C
- D.
C
Correct Answer
A. AExplanation
The correct answer is A because it appears in all the given terms. Therefore, it is a common factor that can be simplified.Rate this question:
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- 10.
Covert the Binary number 1011011000110001010001 into Hexadecimal
- A.
1C8E4
- B.
2D8C51
- C.
D3A4C
- D.
None of these
Correct Answer
B. 2D8C51Explanation
The correct answer is 2D8C51. To convert a binary number to hexadecimal, we group the binary digits into sets of four, starting from the rightmost digit. Then we convert each group of four binary digits into its equivalent hexadecimal digit. In this case, grouping the binary number 1011011000110001010001 into sets of four gives us 0010 1101 1000 1100 0101 0001. Converting each group into hexadecimal gives us 2 D 8 C 5 1, which is the hexadecimal representation of the given binary number.Rate this question:
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- 11.
A device which converts BCD to seven segments is called ……..
- A.
Encoder
- B.
Decoder
- C.
Multiplexer
- D.
None of these
Correct Answer
B. DecoderExplanation
A device that converts Binary Coded Decimal (BCD) to seven segments is called a decoder. A decoder takes the BCD input and produces the appropriate output signals to display the corresponding decimal digit on a seven-segment display. It decodes the BCD input into the correct combination of segments to form the desired digit. Therefore, decoder is the correct answer for this question.Rate this question:
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- 12.
BCD of 43 is
- A.
1010110
- B.
01000011
- C.
100011
- D.
None of these
Correct Answer
B. 01000011Explanation
The answer "01000011" is the correct binary representation of the decimal number 43. In binary, each digit represents a power of 2, starting from the rightmost digit being 2^0. By converting 43 into binary, we find that it is composed of 1 (2^5), 0 (2^4), 0 (2^3), 0 (2^2), 0 (2^1), and 1 (2^0), which gives us "01000011".Rate this question:
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- 13.
Convert the Binary number 1101100101 into Gray code
- A.
1101101011
- B.
1110110101
- C.
1011010111
- D.
None of these
Correct Answer
C. 1011010111Explanation
The correct answer is 1011010111 because to convert a binary number to Gray code, we need to perform an XOR operation between each pair of adjacent bits. Starting from the leftmost bit, the first bit remains the same. For the rest of the bits, we XOR the current bit with the previous bit. In this case, the conversion process would be: 1 (unchanged), 1 XOR 1 = 0, 0 XOR 0 = 0, 1 XOR 0 = 1, 1 XOR 1 = 0, 0 XOR 1 = 1, 1 XOR 0 = 1, 0 XOR 1 = 1, 1 XOR 1 = 0, resulting in 1011010111.Rate this question:
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- 14.
For the gate in the given figure the output will be ………..
- A.
0
- B.
A
- C.
A Compliment
- D.
None of these
Correct Answer
C. A ComplimentExplanation
The correct answer is A Compliment because the gate in the given figure is an inverter gate, also known as a NOT gate. An inverter gate takes an input signal and produces the opposite output signal. In this case, since the output is the complement of the input, the correct answer is A Compliment.Rate this question:
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- 15.
Convert the fractional binary number 0000.1010 to decimal.
- A.
0.50
- B.
0.625
- C.
0.10
- D.
None of these
Correct Answer
B. 0.625Explanation
To convert a fractional binary number to decimal, each digit of the binary number is multiplied by the corresponding power of 2 starting from the rightmost digit. In this case, the binary number is 0000.1010. Multiplying each digit by the corresponding power of 2 gives: 0*2^0 + 0*2^(-1) + 0*2^(-2) + 0*2^(-3) + 1*2^(-4) + 0*2^(-5) + 1*2^(-6) + 0*2^(-7) = 0 + 0 + 0 + 0 + 1/16 + 0 + 1/64 + 0 = 0.625. Therefore, the correct answer is 0.625.Rate this question:
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- 16.
Convert 59.7210 to BCD
- A.
111011
- B.
01011001.01110010
- C.
1110.11
- D.
None of these
Correct Answer
B. 01011001.01110010Explanation
The given number, 59.7210, is converted to BCD format as 01011001.01110010. BCD (Binary-Coded Decimal) is a binary representation of decimal numbers, where each decimal digit is represented by a 4-bit binary code. In this case, each digit of the number is converted to its corresponding 4-bit binary code, resulting in the BCD representation of the number.Rate this question:
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- 17.
IC 7483 is used for
- A.
Binary Addition
- B.
BCD Addition
- C.
Binary Subtraction
- D.
None of these
Correct Answer
B. BCD AdditionExplanation
IC 7483 is a 4-bit parallel adder that is specifically designed for BCD (Binary Coded Decimal) addition. It performs the addition of two 4-bit BCD numbers and produces a 4-bit BCD sum output. This integrated circuit is commonly used in digital systems where BCD addition is required, such as in calculators, digital clocks, and other devices that manipulate BCD numbers. Therefore, the correct answer is BCD Addition.Rate this question:
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- 18.
How is a J-K flip-flop made to toggle?
- A.
J = 0, K = 0
- B.
J = 1, K = 0
- C.
J = 1, K = 1
- D.
None of these
Correct Answer
C. J = 1, K = 1Explanation
When J = 1 and K = 1, it means that both the inputs of the J-K flip-flop are set to 1. In this state, the output of the flip-flop will toggle or change its state with each clock pulse. This means that if the output is initially 0, it will change to 1 on the first clock pulse, and then back to 0 on the next clock pulse, and so on. Therefore, setting J = 1 and K = 1 will make the J-K flip-flop toggle.Rate this question:
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- 19.
On a master-slave flip-flop, when is the master enabled?
- A.
When the gate is LOW
- B.
When the gate is HIGH
- C.
Both of the above
- D.
Neither of the above
Correct Answer
C. Both of the aboveExplanation
The master is enabled in both cases, when the gate is LOW and when the gate is HIGH. This means that the master-slave flip-flop can be triggered and operate correctly regardless of the state of the gate.Rate this question:
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- 20.
The inputs of a NOR gate are connected together. The resulting circuit is ………….
- A.
AND Gate
- B.
OR Gate
- C.
NOT Gate
- D.
NAND Gate
Correct Answer
C. NOT GateExplanation
When the inputs of a NOR gate are connected together, it forms a NOT gate. A NOT gate, also known as an inverter, takes in a single input and produces the opposite output. In the case of a NOR gate with its inputs connected together, both inputs are essentially the same, so the output will be the opposite of the input. Therefore, the resulting circuit is a NOT gate.Rate this question:
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