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420+ Digital Electronics Solved MCQs

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electrical Engineering , Bachelor of Science in Computer Science FY (BSc CS) , Bachelor of Computer Applications (BCA) , Bachelor of Science in Computer Science (BSc CS) .

201.

How many select lines are required for a 1- to-8 demultiplexer?

A. 2
B. 3
C. 4
D. 5
Answer» B. 3
202.

How many AND gates are required for a 1- to-8 multiplexer?

A. 2
B. 6
C. 8
D. 5
Answer» C. 8
203.

Which IC is used for the implementation of 1-to-16 DEMUX?

A. ic 74154
B. ic 74155
C. ic 74139
D. ic 74138
Answer» A. ic 74154
204.

All the comparisons made by comparator is done using                          

A. 1 circuit
B. 2 circuits
C. 3 circuits
D. 4 circuits
Answer» A. 1 circuit
205.

One that is not the outcome of magnitude comparator is                          

A. a > b
B. a – b
C. a < b
D. a = b
Answer» B. a – b
206.

If two numbers are not equal then binary variable will be                          

A. 0
B. 1
C. a
D. b
Answer» A. 0
207.

How many inputs are required for a digital comparator?

A. 1
B. 2
C. 3
D. 4
Answer» B. 2
208.

In a comparator, if we get input as A>B then the output will be                          

A. 1
B. 0
C. a
D. b
Answer» A. 1
209.

Comparators are used in                          

A. memory
B. cpu
C. motherboard
D. hard drive
Answer» B. cpu
210.

A circuit that compares two numbers and determine their magnitude is called

A. height comparator
B. size comparator
C. comparator
D. magnitude comparator
Answer» D. magnitude comparator
211.

A procedure that specifies finite set of steps is called                          

A. algorithm
B. flow chart
C. chart
D. venn diagram
Answer» A. algorithm
212.

How many types of digital comparators are?

A. 1
B. 2
C. 3
D. 4
Answer» B. 2
213.

An identify comparator is defined as a digital comparator which has                          

A. only one output terminal
B. two output terminals
C. three output terminals
D. no output terminal
Answer» A. only one output terminal
214.

A magnitude comparator is defined as a digital comparator which has                          

A. only one output terminal
B. two output terminals
C. three output terminals
D. no output terminal
Answer» C. three output terminals
215.

The purpose of a Digital Comparator is

A. to convert analog input into digital
B. to create different outputs
C. to add a set of different numbers
D. to compare a set of variables or unknown numbers
Answer» D. to compare a set of variables or unknown numbers
216.

TTL 74LS85 is a                            

A. 1-bit digital comparator
B. 4-bit magnitude comparator
C. 8-bit magnitude comparator
D. 8-bit word comparator
Answer» B. 4-bit magnitude comparator
217.

4 to 1 MUX would have                          

A. 2 inputs
B. 3 inputs
C. 4 inputs
D. 5 inputs
Answer» C. 4 inputs
218.

A combinational circuit that selects one from many inputs are                          

A. encoder
B. decoder
C. demultiplexer
D. multiplexer
Answer» D. multiplexer
219.

4 to 1 MUX would have                          

A. 1 output
B. 2 outputs
C. 3 outputs
D. 4 outputs
Answer» A. 1 output
220.

Which of the following circuit can be used as parallel to serial converter?

A. multiplexer
B. demultiplexer
C. decoder
D. digital counter
Answer» A. multiplexer
221.

The inputs/outputs of an analog multiplexer/demultiplexer are                          

A. bidirectional
B. unidirectional
C. even parity
D. binary-coded decimal
Answer» A. bidirectional
222.

If enable input is high then the multiplexer is                              

A. enable
B. disable
C. saturation
D. high impedance
Answer» B. disable
223.

What is data routing in a multiplexer?

A. it spreads the information to the control unit
B. it can be used to route data from one of several source to destination
C. it is an application of multiplexer
D. both it can be used to route data and it is an application of multiplexer
Answer» D. both it can be used to route data and it is an application of multiplexer
224.

How many inputs will a decimal-to-BCD encoder have?

A. 4
B. 8
C. 10
D. 16
Answer» C. 10
225.

How many outputs will a decimal-to-BCD encoder have?

A. 4
B. 8
C. 12
D. 16
Answer» A. 4
226.

How is an encoder different from a decoder?

A. the output of an encoder is a binary code for 1-of-n input
B. the output of a decoder is a binary code for 1-of-n input
C. the output of an encoder is a binary code for n-of-1 output
D. the output of a decoder is a binary code for n-of-1 output
Answer» A. the output of an encoder is a binary code for 1-of-n input
227.

If we record any music in any recorder, such types of process is called                        

A. multiplexing
B. encoding
C. decoding
D. demultiplexing
Answer» B. encoding
228.

Can an encoder be a transducer?

A. yes
B. no
C. may or may not be
D. both are not even related slightly
Answer» A. yes
229.

How many OR gates are required for a Decimal-to-bcd encoder?

A. 2
B. 10
C. 3
D. 4
Answer» D. 4
230.

How many OR gates are required for an octal-to-binary encoder?

A. 3
B. 2
C. 8
D. 10
Answer» A. 3
231.

Can an encoder be called as multiplexer?

A. no
B. yes
C. sometimes
D. never
Answer» B. yes
232.

If two inputs are active on a priority encoder, which will be coded on the output?

A. the higher value
B. the lower value
C. neither of the inputs
D. both of the inputs
Answer» A. the higher value
233.

Latches constructed with NOR and NAND gates tend to remain in the latched condition due to which configuration feature?

A. low input voltages
B. synchronous operation
C. gate impedance
D. cross coupling
Answer» D. cross coupling
234.

One example of the use of an S-R flip-flop is as                        

A. transition pulse generator
B. racer
C. switch debouncer
D. astable oscillator
Answer» C. switch debouncer
235.

The truth table for an S-R flip-flop has how many VALID entries?

A. 1
B. 2
C. 3
D. 4
Answer» C. 3
236.

When both inputs of a J-K flip-flop cycle, the output will                        

A. be invalid
B. change
C. not change
D. toggle
Answer» C. not change
237.

Which of the following is correct for a gated D-type flip-flop?

A. the q output is either set or reset as soon as the d input goes high or low
B. the output complement follows the input when enabled
C. only one of the inputs can be high at a time
D. the output toggles if one of the inputs is held high
Answer» A. the q output is either set or reset as soon as the d input goes high or low
238.

A basic S-R flip-flop can be constructed by cross-coupling of which basic logic gates?

A. and or or gates
B. xor or xnor gates
C. nor or nand gates
D. and or nor gates
Answer» C. nor or nand gates
239.

The logic circuits whose outputs at any instant of time depends only on the present input but also on the past outputs are called

A. combinational circuits
B. sequential circuits
C. latches
D. flip-flops
Answer» B. sequential circuits
240.

Whose operations are more faster among the following?

A. combinational circuits
B. sequential circuits
C. latches
D. flip-flops
Answer» A. combinational circuits
241.

How many types of sequential circuits are?

A. 2
B. 3
C. 4
D. 5
Answer» A. 2
242.

The sequential circuit is also called

A. flip-flop
B. latch
C. strobe
D. adder
Answer» B. latch
243.

The basic latch consists of                        

A. two inverters
B. two comparators
C. two amplifiers
D. two adders
Answer» A. two inverters
244.

In S-R flip-flop, if Q = 0 the output is said to be                        

A. set
B. reset
C. previous state
D. current state
Answer» B. reset
245.

The output of latches will remain in set/reset untill                        

A. the trigger pulse is given to change the state
B. any pulse given to go into previous state
C. they don’t get any pulse more
D. the pulse is edge-triggered
Answer» A. the trigger pulse is given to change the state
246.

What is a trigger pulse?

A. a pulse that starts a cycle of operation
B. a pulse that reverses the cycle of operation
C. a pulse that prevents a cycle of operation
D. a pulse that enhances a cycle of operation
Answer» A. a pulse that starts a cycle of operation
247.

The circuits of NOR based S-R latch classified as asynchronous sequential circuits, why?

A. because of inverted outputs
B. because of triggering functionality
C. because of cross-coupled connection
D. because of inverted outputs & triggering functionality
Answer» C. because of cross-coupled connection
248.

Which are easier to design?

A. clocked circuits
B. asynchronous sequential circuits
C. clocked circuits with buffer
D. asynchronous sequential circuits with buffers
Answer» A. clocked circuits
249.

                       is used to drive high capacitance load.

A. single polar capability
B. bipolar capability
C. tripolar capability
D. bi and tri polar capability
Answer» B. bipolar capability
250.

As the temperature is increased, storage time                          

A. halved
B. doubled
C. does not change
D. tripled
Answer» A. halved

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