Digital Electronics MCQ

1. The basic unit of digital information is:

a) Byte

b) Bit

c) Nibble

d) Word

Answer:

b) Bit

Explanation:

The bit (binary digit) is the most basic unit of information in digital electronics and computing, representing a 0 or 1.

2. A flip-flop is a:

a) Digital amplifier

b) Voltage regulator

c) Memory storage device

d) Signal modulator

Answer:

c) Memory storage device

Explanation:

A flip-flop is a basic memory storage device used in digital electronics, capable of storing one bit of data.

3. The primary function of a decoder is to:

a) Encode digital data

b) Convert analog to digital

c) Expand a digital signal into multiple outputs

d) Compress digital data

Answer:

c) Expand a digital signal into multiple outputs

Explanation:

A decoder takes a smaller number of input signals and expands them into a larger number of outputs.

4. An AND gate gives a high output (1) when:

a) Any input is high

b) All inputs are low

c) All inputs are high

d) No input is high

Answer:

c) All inputs are high

Explanation:

An AND gate outputs a high (1) only when all of its inputs are high (1).

5. What does the term 'LSB' stand for in digital electronics?

a) Least Significant Bit

b) Last Significant Byte

c) Longest Signal Band

d) Least Signal Byte

Answer:

a) Least Significant Bit

Explanation:

LSB stands for Least Significant Bit, referring to the bit in a binary number representing the smallest value.

6. EEPROM stands for:

a) Electrically Erasable Programmable Read-Only Memory

b) Electronic Erasable Programmable Read-Only Memory

c) Electrically Enabled Programmable Read-Only Memory

d) Electronic Enabled Programmable Read-Only Memory

Answer:

a) Electrically Erasable Programmable Read-Only Memory

Explanation:

EEPROM is a type of non-volatile memory used in computers and other devices to store data that must be saved when power is removed.

7. The binary number '1010' is equivalent to what decimal number?

a) 8

b) 10

c) 12

d) 14

Answer:

b) 10

Explanation:

The binary number 1010 is equal to 10 in decimal (1*2^3 + 0*2^2 + 1*2^1 + 0*2^0).

8. In digital circuits, a multiplexer is used to:

a) Combine several inputs into one output

b) Split one input into several outputs

c) Amplify digital signals

d) Store data

Answer:

a) Combine several inputs into one output

Explanation:

A multiplexer selects one of several input signals and forwards the selected input into a single line.

9. A seven-segment display is commonly used to display:

a) Binary numbers

b) Hexadecimal numbers

c) Decimal digits

d) ASCII characters

Answer:

c) Decimal digits

Explanation:

A seven-segment display is typically used to display decimal digits and some alphabetic characters.

10. CMOS technology is known for its:

a) High speed

b) High power consumption

c) Low power consumption

d) Large size

Answer:

c) Low power consumption

Explanation:

CMOS (Complementary Metal-Oxide-Semiconductor) technology is widely used in digital circuits due to its low power consumption.

11. The primary function of an XOR gate is to:

a) Output high when all inputs are the same

b) Output high when any input is high

c) Output high when inputs are different

d) Always output low

Answer:

c) Output high when inputs are different

Explanation:

An XOR (Exclusive OR) gate outputs high only when the inputs are different from each other.

12. In digital logic, a 'latch' is used to:

a) Convert analog signals to digital

b) Store a single bit of data

c) Increase signal strength

d) Combine multiple signals

Answer:

b) Store a single bit of data

Explanation:

A latch is a basic memory device in digital electronics, capable of storing one bit of data.

13. The main advantage of digital signals over analog signals is:

a) Higher speed

b) Better quality

c) Less susceptibility to noise

d) Higher voltage levels

Answer:

c) Less susceptibility to noise

Explanation:

Digital signals are less susceptible to noise and distortion compared to analog signals, leading to more reliable data transmission.

14. A full adder circuit adds:

a) Two bits

b) Three bits

c) Four bits

d) Two bytes

Answer:

b) Three bits

Explanation:

A full adder adds three bits (two input bits and a carry bit) and produces a sum and a carry output.

15. The Boolean expression for a NAND gate is:

a) \( A + B \)

b) \( A \cdot B \)

c) \( \overline{A \cdot B} \)

d) \( \overline{A + B} \)

Answer:

c) \( \overline{A \cdot B} \)

Explanation:

A NAND gate produces an output which is the negation of the AND operation on its inputs, represented as \( \overline{A \cdot B} \).

16. What is the primary use of a shift register?

a) Data storage

b) Data transfer

c) Data conversion

d) Data manipulation

Answer:

b) Data transfer

Explanation:

A shift register is mainly used for the transfer of data in serial or parallel form.

17. The process of converting analog signals to digital is called:

a) Multiplexing

b) Demodulation

c) Modulation

d) Sampling

Answer:

d) Sampling

Explanation:

Sampling is the process of converting an analog signal into a digital signal by measuring its amplitude at regular intervals.

18. A digital circuit capable of holding a single binary digit is called a:

a) Decoder

b) Multiplexer

c) Bit

d) Flip-Flop

Answer:

d) Flip-Flop

Explanation:

A flip-flop is a digital circuit used for storing a single binary digit or bit.

19. The main component used in the first generation of computers was:

a) Transistors

b) Vacuum tubes

c) Integrated circuits

d) Microprocessors

Answer:

b) Vacuum tubes

Explanation:

The first generation of computers primarily used vacuum tubes as their main electronic component.

20. A parity bit is used for:

a) Error detection

b) Data encryption

c) Increasing data speed

d) Data compression

Answer:

a) Error detection

Explanation:

A parity bit is added to a set of binary data to make the number of set bits either even (even parity) or odd (odd parity), used for error detection purposes. 21. The main purpose of a digital-to-analog converter (DAC) is to: a) Convert digital signals to analog format b) Convert analog signals to digital format c) Increase the speed of digital signals d) Compress digital data

22. A 'Logic High' in TTL (Transistor-Transistor Logic) circuits is typically:

a) 0V to 0.8V

b) 2V to 5V

c) 5V

d) Above 5V

Answer:

b) 2V to 5V

Explanation:

In TTL circuits, a 'Logic High' is typically in the range of 2V to 5V.

23. The primary characteristic of a synchronous circuit is that:

a) It operates without a clock signal

b) Its operations are driven by a clock signal

c) It is faster than an asynchronous circuit

d) It does not require a power source

Answer:

b) Its operations are driven by a clock signal

Explanation:

Synchronous circuits use a clock signal to synchronize the operations of its components.

24. A Karnaugh map is used in digital electronics to:

a) Simplify Boolean expressions

b) Design complex circuits

c) Store binary data

d) Convert binary to hexadecimal

Answer:

a) Simplify Boolean expressions

Explanation:

A Karnaugh map is a diagrammatic method used to simplify Boolean algebra expressions.

25. The main advantage of CMOS over NMOS technology is:

a) Higher speed

b) Lower power consumption

c) Larger size

d) Higher voltage requirement

Answer:

b) Lower power consumption

Explanation:

CMOS (Complementary Metal-Oxide-Semiconductor) technology offers the advantage of lower power consumption compared to NMOS (N-Channel Metal-Oxide-Semiconductor) technology.