ISCET Digital Electronics Principles Questions and Answers

Question 1

Which of the following Boolean expressions correctly represents one of De Morgan's theorems?

Accepted Answer

NOT (A AND B) = (NOT A) OR (NOT B)

Answer

A AND B

Answer

NOT (A AND B) = (NOT A) AND (NOT B)

Answer

NOT (A OR B) = (NOT A) OR (NOT B)

Question 2

A technician is designing a circuit that needs to select one of eight data inputs and route it to a single output. Which digital logic device is most suitable for this task?

Accepted Answer

Multiplexer (MUX)

Answer

Demultiplexer (DEMUX)

Answer

Encoder

Answer

Decoder

Question 3

In a J-K flip-flop, what is the output behavior when both J and K inputs are held HIGH (logic 1) and a clock pulse is applied?

Accepted Answer

The output toggles to the opposite state.

Answer

The output remains in its previous state.

Answer

The output is reset to 0 (LOW).

Answer

The output is set to 1 (HIGH).

Question 4

A technician is using a Karnaugh map (K-map) to simplify a 4-variable Boolean expression. How many cells will the K-map contain?

Accepted Answer

16

Answer

4

Answer

8

Answer

32

Question 5

What is the key difference between a latch and a flip-flop in digital sequential circuits?

Accepted Answer

Latches are level-triggered, while flip-flops are edge-triggered.

Answer

Latches are made from logic gates, while flip-flops are not.

Answer

Latches can store more bits of data than flip-flops.

Answer

Latches operate asynchronously, while flip-flops operate synchronously.

Question 6

A technician is troubleshooting a digital logic circuit and finds that the output of a specific IC is always LOW, regardless of the inputs. The VCC and GND pins are confirmed to have the correct voltage. Which of the following is the most likely fault?

Accepted Answer

The output of the IC is internally shorted to ground.

Answer

An open circuit on one of the logic inputs.

Answer

The subsequent IC in the signal path has a shorted input.

Answer

The system clock frequency is too high.