Digital Electronics MCQ & Objective Questions
Digital Electronics is a crucial subject for students preparing for school and competitive exams in India. Mastering this topic not only enhances your understanding of electronic systems but also significantly boosts your exam scores. Practicing MCQs and objective questions in Digital Electronics helps you identify important concepts and improves your problem-solving skills, making it an essential part of your exam preparation.
What You Will Practise Here
Fundamentals of digital logic design
Binary number systems and conversions
Logic gates and their truth tables
Combinational circuits and their applications
Sequential circuits and flip-flops
Boolean algebra and simplification techniques
Key definitions and important formulas
Exam Relevance
Digital Electronics is a significant topic in various examinations, including CBSE, State Boards, NEET, and JEE. Students can expect questions related to logic gates, number systems, and circuit design. Common patterns include multiple-choice questions that test both theoretical knowledge and practical applications, making it vital to be well-prepared with important Digital Electronics questions for exams.
Common Mistakes Students Make
Confusing between different types of logic gates and their functions.
Misunderstanding the conversion processes between binary and decimal systems.
Overlooking the importance of truth tables in combinational circuits.
Failing to apply Boolean algebra correctly in simplification problems.
Neglecting the timing diagrams in sequential circuits.
FAQs
Question: What are the key topics I should focus on in Digital Electronics for exams?Answer: Focus on logic gates, number systems, combinational and sequential circuits, and Boolean algebra.
Question: How can I improve my performance in Digital Electronics MCQs?Answer: Regular practice of MCQs and understanding the underlying concepts will greatly enhance your performance.
Start solving practice MCQs today to test your understanding and solidify your knowledge in Digital Electronics. Remember, consistent practice is the key to success in your exams!
Q. What is the main difference between synchronous and asynchronous counters?
A.
Synchronous counters count faster
B.
Asynchronous counters have a delay
C.
Synchronous counters are simpler
D.
Asynchronous counters are more accurate
Show solution
Solution
Asynchronous counters have a propagation delay due to the ripple effect, while synchronous counters change states simultaneously.
Correct Answer:
B
— Asynchronous counters have a delay
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Q. What is the main disadvantage of using CMOS logic?
A.
High power consumption
B.
Complex design
C.
Susceptibility to noise
D.
Slower than TTL
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Solution
CMOS logic can be more complex to design due to the need for complementary pairs of transistors.
Correct Answer:
C
— Susceptibility to noise
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Q. What is the main function of a fuse in a programmable logic device?
A.
To store data
B.
To connect logic gates
C.
To provide power
D.
To reset the device
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Solution
In a programmable logic device, a fuse is used to connect logic gates, allowing the device to be configured for specific logic functions.
Correct Answer:
B
— To connect logic gates
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Q. What is the main purpose of a decoder in digital circuits?
A.
To convert binary data to decimal
B.
To select specific outputs based on input combinations
C.
To perform arithmetic operations
D.
To store data
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Solution
A decoder converts binary input into a unique output line, selecting specific outputs based on input combinations.
Correct Answer:
B
— To select specific outputs based on input combinations
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Q. What is the main purpose of using pull-up resistors in TTL circuits?
A.
To increase speed
B.
To ensure a defined logic level
C.
To reduce power consumption
D.
To improve noise immunity
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Solution
Pull-up resistors are used to ensure that inputs are at a defined logic level when not actively driven.
Correct Answer:
B
— To ensure a defined logic level
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Q. What is the maximum capacity of a standard DVD?
A.
4.7 GB
B.
8.5 GB
C.
25 GB
D.
50 GB
Show solution
Solution
A standard single-layer DVD can hold up to 4.7 GB of data.
Correct Answer:
A
— 4.7 GB
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Q. What is the maximum clock frequency of the 8051 microcontroller?
A.
1 MHz
B.
12 MHz
C.
24 MHz
D.
40 MHz
Show solution
Solution
The maximum clock frequency of the 8051 microcontroller is 12 MHz.
Correct Answer:
B
— 12 MHz
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Q. What is the maximum output current of a standard 555 timer?
A.
10 mA
B.
20 mA
C.
200 mA
D.
500 mA
Show solution
Solution
The maximum output current of a standard 555 timer is typically around 20 mA.
Correct Answer:
B
— 20 mA
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Q. What is the maximum theoretical capacity of a single-layer DVD?
A.
4.7 GB
B.
8.5 GB
C.
25 GB
D.
50 GB
Show solution
Solution
A single-layer DVD has a maximum theoretical capacity of 4.7 GB.
Correct Answer:
A
— 4.7 GB
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Q. What is the Nyquist theorem related to?
A.
The maximum frequency of a signal
B.
The minimum sampling rate to avoid aliasing
C.
The bandwidth of a digital filter
D.
The energy of a signal
Show solution
Solution
The Nyquist theorem states that to avoid aliasing, a signal must be sampled at least twice its maximum frequency.
Correct Answer:
B
— The minimum sampling rate to avoid aliasing
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Q. What is the octal representation of the decimal number 8?
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Solution
The octal representation of decimal 8 is 10.
Correct Answer:
A
— 10
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Q. What is the output of a 2-bit binary adder for inputs 11 and 01?
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Solution
11 + 01 = 100 in binary, which is 4 in decimal.
Correct Answer:
D
— 100
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Q. What is the output of a 2-bit binary counter after three clock pulses?
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Solution
After three clock pulses, a 2-bit binary counter will output 10 (which is 2 in decimal).
Correct Answer:
C
— 10
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Q. What is the output of a 2-input AND gate when both inputs are high?
A.
0
B.
1
C.
Undefined
D.
Both 0 and 1
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Solution
An AND gate outputs high (1) only when both inputs are high (1).
Correct Answer:
B
— 1
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Q. What is the output of a 2-input AND gate when both inputs are true?
A.
0
B.
1
C.
undefined
D.
false
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Solution
A 2-input AND gate outputs 1 (true) when both inputs are true.
Correct Answer:
B
— 1
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Q. What is the output of a 2-input NAND gate when both inputs are low?
A.
0
B.
1
C.
Undefined
D.
Depends on the circuit
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Solution
A NAND gate outputs high (1) when at least one input is low (0).
Correct Answer:
B
— 1
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Q. What is the output of a 2-input NOR gate when both inputs are high?
A.
0
B.
1
C.
Both 0 and 1
D.
Undefined
Show solution
Solution
A 2-input NOR gate outputs 0 when at least one of its inputs is high; it only outputs 1 when both inputs are low.
Correct Answer:
A
— 0
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Q. What is the output of a 2-input NOR gate when both inputs are low?
A.
0
B.
1
C.
Undefined
D.
Depends on the circuit
Show solution
Solution
A NOR gate outputs high (1) only when both inputs are low (0).
Correct Answer:
B
— 1
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Q. What is the output of a 2-input OR gate when one input is low and the other is high?
A.
0
B.
1
C.
Both 0 and 1
D.
Undefined
Show solution
Solution
An OR gate outputs high (1) if at least one input is high (1).
Correct Answer:
B
— 1
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Q. What is the output of a 2-input XOR gate when both inputs are the same?
A.
0
B.
1
C.
Undefined
D.
Depends on the circuit
Show solution
Solution
An XOR gate outputs low (0) when both inputs are the same (either both 0 or both 1).
Correct Answer:
A
— 0
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Q. What is the output of a 2-to-1 multiplexer if the inputs are A=0, B=1 and the select line is 0?
A.
0
B.
1
C.
Undefined
D.
Both 0 and 1
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Solution
If the select line is 0, the output of the 2-to-1 multiplexer will be the value of input A, which is 0.
Correct Answer:
A
— 0
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Q. What is the output of a 3-bit counter after 5 clock pulses?
A.
000
B.
101
C.
011
D.
111
Show solution
Solution
After 5 clock pulses, a 3-bit counter will output 101 in binary.
Correct Answer:
B
— 101
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Q. What is the output of a 3-input XOR gate when all inputs are high?
A.
0
B.
1
C.
Undefined
D.
Both 0 and 1
Show solution
Solution
A 3-input XOR gate outputs high (1) if an odd number of inputs are high; with all inputs high, it outputs low (0).
Correct Answer:
A
— 0
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Q. What is the output of a 4-to-1 multiplexer if the inputs are A=0, B=1, C=0, D=1 and the select lines are S0=1, S1=0?
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Solution
The select lines S0=1 and S1=0 select input B, which is 1.
Correct Answer:
B
— 1
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Q. What is the output of a binary to BCD converter for the binary input 10010?
A.
0010
B.
0001 0010
C.
0001 0000
D.
0011
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Solution
The binary input 10010 is equal to decimal 18, which is represented in BCD as 0001 0010.
Correct Answer:
B
— 0001 0010
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Q. What is the output of a binary to BCD converter for the binary input 1001?
A.
0001 0001
B.
0000 1001
C.
0000 0001
D.
0000 1000
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Solution
The binary input 1001 is equal to 9 in decimal, which is represented as 0000 1001 in BCD.
Correct Answer:
B
— 0000 1001
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Q. What is the output of a binary to gray code converter for the binary input 1011?
A.
1110
B.
1100
C.
1001
D.
1010
Show solution
Solution
The gray code equivalent of the binary number 1011 is 1110.
Correct Answer:
A
— 1110
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Q. What is the output of a D Flip-Flop when the D input is low and the clock signal transitions?
A.
High
B.
Low
C.
Toggle
D.
Undefined
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Solution
The output of a D Flip-Flop will be low when the D input is low at the time of the clock transition.
Correct Answer:
B
— Low
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Q. What is the output of a decimal to binary converter for the decimal number 10?
A.
1010
B.
1001
C.
1100
D.
1110
Show solution
Solution
The binary equivalent of the decimal number 10 is 1010.
Correct Answer:
A
— 1010
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Q. What is the output of a NAND gate if both inputs are 1?
A.
0
B.
1
C.
undefined
D.
error
Show solution
Solution
A NAND gate outputs 0 only when both inputs are 1; otherwise, it outputs 1.
Correct Answer:
A
— 0
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