# Digital Electronics : 100 Most Important Questions with Solutions

By Yash Bansal|Updated : March 26th, 2021

You have completed the syllabus of the RVUNL exam for Digital Electronics. Now BYJU'S Exam Prep brings you the 100 most important questions of the Digital Electronics subject.

Here you will find the 100 most important questions for the Digital Electronics subject of the Electrical  Engineering syllabus. The top 10 questions are attached here rest questions you can find in the below pdf.

## PDF OF 100 MOST IMPORTANT QUESTIONS OF DIGITAL ELECTRONICS

You have completed the syllabus of the RVUNL exam for Digital Electronics. Now BYJU'S Exam Prep brings you the 100 most important questions of the Digital Electronics subject.

Here you will find the 100 most important questions for the Digital Electronics subject of the Electrical Engineering syllabus. The top 10 questions are attached here rest questions you can find in the below pdf.

## PDF OF 100 MOST IMPORTANT QUESTIONS OF Digital Electronics

1. The duty cycle of the most significant bit (MSB) from a 4-bit BCD counter is ____________

A. 20%
B. 50%
C. 10%
D. 80%

Solution:

There are 10 states, out of which MSB is high only for (1000, 1001) 2 times. Hence duty cycle is 2/10*100 = 20%. Since the duty cycle is the ratio of on-time to the total time.

2. Identify the combinational logic circuit(s) from the following list:

2. J-K flip-flop
3. Counter

A. 2 only
B. 3 only
C. 2 and 3
D. 1 only

Solution:

The combinational circuits are:

2. Full subtractor
3. Multiplexers
4. De-multiplexers
5. Encoders
6. Decoders

3. UP-DOWN counter is also known as ___________.

A. Dual counter
B. Multi counter
C. Multimode counter
D. Two Counter

Solution:

UP-DOWN counter is also known as multimode counter because it has capability of counting upward as well as downwards.

4. A JK flip-flop can be made to function like a T flip-flop by simply,

A. connecting the J and K inputs together as one-input
B. connecting J = 0 and K = 0
C. resetting all inputs of the JK
D. connecting earth ground the JK inputs

Solution:

If you short the J and K terminals of JK flip-flop it becomes T flip-flop.
Because if you give J = 0 and K= 0 present state remains as it is and if you give J = 1 and K= 1 present state gets toggled.

5. The smallest resistor in an 8 bit weighted resistor DAC is 5kΩ, what will be the largest resistor value?

A. 2.56MΩ
B. 1.28MΩ
C. 1.28KΩ
D. 2.56KΩ

Solution:

The largest resistor value for 8-bit DAC= 2n×R = 28×5kΩ = 256×5kΩ =1.28MΩ

6.

The state of the flip-flop after the occurrence of a clock pulse is called as its
A. current state
B. present state
C. next state
D. current input

Solution:

The state of the flip-flop before the occurrence of clock pulse is called as its next state.

7. For a serial in serial out register of 4 bits time taken for output of 4 bits is

A. 4
B. 5
C. 3
D. 1

Solution:

For serial In serial Out the date to be seen at output (n-1) clock pulse will be needed where n is number of bits. 4 bits are there so (4-1)=3 clock pulse will be needed to obtain In at Out.
At 3rd clock pulse data at In will be shown at Out.

8. If F = AB + A'B' Boolean expression is to be implemented using decoders and OR gates, the connection involves

A. 2 to 4 line decoder with 3 OR gates
B. 3 to 8 line decoder with 2 OR gates
C. 2 to 4 line decoder with 1 OR gates
D. 3 to 8 line decoder with 4 OR gates

Solution |||

F = AB + A'B' Boolean expression is to be implemented using decoders and OR gates, the connection involves 2 to 4 line decoder with 1 OR gates.

If you add D1 and D2 with OR gate you will get F = AB + A'B'.

You can avail of Online Classroom Program for all AE & JE Exams:

## Online Classroom Program for AE & JE Exams (12+ Structured LIVE Courses and 160+ Mock Tests)

You can avail of BYJU'S Exam Prep Test Series specially designed for all AE & JE Exams:

## BYJU'S Exam Prep Test Series AE & JE (160+ Mock Tests)

thanks,

Team BYJU'S Exam Prep

Sahi Prep Hai to Life Set HAI GradeStack Learning Pvt. Ltd.Windsor IT Park, Tower - A, 2nd Floor, Sector 125, Noida, Uttar Pradesh 201303 bepstudentsupport@byjus.com