BEE FREE Bachelor of Electrical Engineering Digital Circuits Questions and Answers 2 — Questions and Answers
Question 1: What is the output of an XOR gate when both inputs are logic 1?
- 0 (Correct answer)
- 1
- Undefined
- High impedance
Correct answer: 0
An XOR gate produces a 0 output when both inputs are identical.
Question 2: Which flip-flop is used to divide the input clock frequency by 2?
- T flip-flop with T=1 (Correct answer)
- D flip-flop with D=0
- SR flip-flop with S=1
- JK flip-flop with J=0, K=0
Correct answer: T flip-flop with T=1
A T flip-flop with T tied to 1 toggles on every clock edge, producing a frequency that is half the input clock.
Question 3: How many 2-to-1 multiplexers are needed to build a 4-to-1 multiplexer?
- 3 (Correct answer)
- 2
- 4
- 1
Correct answer: 3
A 4-to-1 MUX requires two 2-to-1 MUXes at the first stage and one at the second stage, totaling three.
Question 4: What is the minimum number of NAND gates required to implement a NOT gate?
- 1 (Correct answer)
- 2
- 3
- 4
Correct answer: 1
Connecting both inputs of a NAND gate together produces the complement of the input, functioning as a NOT gate.
Question 5: In a 4-bit binary ripple counter, what is the maximum count value before it resets to zero?
- 15 (Correct answer)
- 16
- 10
- 8
Correct answer: 15
A 4-bit counter counts from 0 to 2^4 − 1 = 15 before rolling over to zero.
Question 6: Which Boolean expression represents the consensus theorem?
- AB + A'C + BC = AB + A'C (Correct answer)
- AB + A'C + BC = AB + BC
- AB + A'C + BC = A'C + BC
- AB + A'C + BC = AB + A'C + ABC
Correct answer: AB + A'C + BC = AB + A'C
The consensus theorem states that the term BC is redundant when both AB and A'C are present.
BEE FREE Bachelor of Electrical Engineering Digital Circuits Questions and Answers 2
What is the output of an XOR gate when both inputs are logic 1?