Digital Electronics Objective Questions:



Que 1. The Boolean experssion Y=AB + CD represents

1) Two ORs ANDed together
2) A 4 input AND gate
3) Two ANDs ORed together
4) An exclusive OR

Ans: Two ANDs ORed together

Que 2. A 4 bit module 6 ripple counter uses JK flip flop. If the propogation by each flip flop is 50 ns . The maximum clock  frequency be used

1) 5 MHz
2) 10 MHz
3) 4 MHz
4) 20 MHz

Ans: 5 MHz

Que 3. MOD12 and MOD6 counters and multipliers are most commonly used as

1) Frequency counters
2) Multiplexed displays
3) Power consumption meters
4) Digital Colcks

Ans: Digital Clocks

Que 4. Decimal counter using flipflops and feedback, are more popular than a decimal counter of ring type because of

1) simple decade circuitary required
2) economy in the number of flipflops
3) high speed of operation
4) its availability in IC form

Ans: economy in the number of flipflops

Que 5. Transparent Flip Flops are also called as

1) Latches
2) Asynchronous Flip Flops
3) Multiplexers
4) Both Latches & Asynchronous Flip Flops

Ans: Asynchronous Flip Flops

Que 6. 63 in Decimal System can be written in Binary Systems as

1) 111100
2) 111101
3) 111111
4) 101010

Ans: 111111


Que 7. If A and B are two input in AND gates, the AND gate has output of 1, when the values of A and B are

1) A=0,B=0
2) A=1,B=1
3) A=1, B=0
4) A=0, B=1
Ans: A=0, B=0

Que 8. A string of 4 bits is called as

1) Bit
2) Byte
3) Word
4) Nibble

Ans: Nibble

Que 9. The 9's complement of a Decimal digit is the

1) 1's Complement of the Excess 3 code for the Digit
2) 2's Complement of the Excess 3 code for the Digit
3) 1's Complement of the Excess 4 code for the Digit
4) 2's Complement of the Excess 4 code for the Digit

Ans: 1's Complement of the Excess 3 code for the Digit

Que 10. Hexadecimal equivalent of binary number 10001101011001 is

1) 2359
2) 9493
3) 8D62
4) 8DF2

Ans: 2359

Que 11. Which of the following statement is true?

1) A+ AB = A
2) A(A+ = AB
3) CA + CAB = CA +CB
4) None of these

Ans: A+ AB = A

Que 12. In Boolean algebra, the term sum of products means

1) the AND function of several OR functions
2) the OR function of several AND functions
3) the OR function of several OR functions
4) the AND function of several AND functions

Ans: the OR function of several AND functions

Que 13. The output of a sequential circuit depends on

1) present inputs
2) past outputs
3) both present and past inputs
4) past inputs

Ans: both present and past inputs

Que 14. A multiplexer is also known as

1) counter
2) decoder
3) data selector
4) none of these

Ans: data selector

Que 15. Binary 11110 equals ____ in hexadecimal

1) 2A
2) 2E
3) 1E
4) 2C

Ans: 2A

Que 16. Gate is a circuit with one or more input but output is

1) two
2) one
3) three
4) more than 1

Ans: two

Que 17. _____ data transmission is more useful when sending information for long distances

1) Serial
2) Parallel
3) Either
4) Neither

Ans: Neither

Que 18. The Boolean function Y = AB + CD is to be realized using only 2 input NAND gates. The minimum number of gates required is

1) 2
2) 3
3) 4
4) 5

Ans: 3


Que 19.The Characteristic equation of T flip flop is

1) Q= T'Q+TQ'
2) Q=T'Q'+QT'
3) Q=TQ
4) Q=TQ'

Ans: Q= T'Q+TQ'

Que 20. Which of the following logic circuits accepts two binary digits on its inputs and produce

1) full adder
2) half adder
3) decoder
4) multiplexer

Ans: half adder

Que 21. Which of the following circuit can be used as parallel to serial convertor
1) digital counter
2) decoder
3) demultiplexer
4) multiplexer

Ans: multiplexer


Que 22. When the Input to a seven segment decoder is "0100" the number on display will be

1) 0
2) 2
3) 4
4) 9

Ans: 4

Que 23. Which of the following hexadecimal numbers represents an odd decimal number

1) FF
2) EG
3) CC
4) AA

Ans: FF

Que 24. Half adder is also known as

1) AND circuit
2) NAND circuit
3) NOR circuit
4) EXOR circuit

Ans: EXOR circuit

Que 25. Logic 1 in positive logic system is represented by

1) zero level
2) lower voltage level
3) higher voltage level
4) negative voltage

Ans: higher voltage level