Digital Electronics MCQ


1.The binary number 10101 is equivalent to decimal number …………..

1.     19

2.     12

3.     27

4.     21

Answer : 4

 

2.The inverter is ……………

1.     NOT gate

2.     OR gate

3.     AND gate

4.     None of the above

Answer : 1

 

3. The inputs of a NAND gate are connected together. The resulting circuit is ………….

1.     OR gate

2.     AND gate

3.     NOT gate

4.     None of the above

Answer : 3

 

4.The NOR gate is OR gate followed by ………………

1.     AND gate

2.     NAND gate

3.     NOT gate

4.     None of the above

 

Answer : 4

 

 5.The universal gate is ………………

1.     NAND gate

2.     OR gate

3.     AND gate

4.     None of the above

Answer : 1

 

 6.Digital circuit can be made by the repeated use of ………………

1.     OR gates

2.     NOT gates

3.     NAND gates

4.     None of the above

Answer : 3

 

7.The only function of NOT gate is to ……………..

1.     Stop signal

2.     Invert input signal

3.     Act as a universal gate

4.     None of the above

Answer : 2

 

8.When an input signal 1 is applied to a NOT gate, the output is ………………

1.     0

2.     1

3.     Either 0 & 1

4.     None of the above

Answer : 1

 

 9.Digital circuit can be made by the repeated use of ………………

1.     OR gates

2.     NOT gates

3.     NAND gates

4.     None of the above

Answer : 3

 

10.The only function of NOT gate is to ……………..

1.     Stop signal

2.     Invert input signal

3.     Act as a universal gate

4.     None of the above

Answer : 2

 

11.When an input signal 1 is applied to a NOT gate, the output is ………………

1.     0

2.     1

3.     Either 0 & 1

4.     None of the above

Answer : 1

 12.In Boolean algebra, the bar sign (-) indicates ………………..

1.     OR operation

2.     AND operation

3.     NOT operation

4.     None of the above

Answer : 3

13. The resolution of an n bit DAC with a maximum input of 5 V is 5 mV. The value of n is …….

1.     8

2.     9

3.     10

4.     11

Answer : 3

14. 2’s complement of binary number 0101 is ………..

1.     1011

2.     1111

3.     1101

4.     1110

Answer : 1

14. An OR gate has 4 inputs. One input is high and the other three are low. The output is …….

1.     Low

2.     High

3.     alternately high and low

4.     may be high or low depending on relative magnitude of inputs

Answer : 2

 

15.. Decimal number 10 is equal to binary number ……………

1.     1110

2.     1010

3.     1001

4.     1000

Answer : 2

16. Both OR and AND gates can have only two inputs.

1.     True

2.     False

Answer : 2

17. A device which converts BCD to seven segments is called ……..

1.     Encoder

2.     Decoder

3.     Multiplexer

4.     None of these

Answer : 2

 

18. In 2’s complement representation the number 11100101 represents the decimal number ……………

1.     +37

2.     -31

3.     +27

4.     -27

Answer : 4

19. A decade counter skips ………..

1.     binary states 1000 to 1111

2.     binary states 0000 to 0011

3.     binary states 1010 to 1111

4.     binary states 1111 to higher

Answer : 3

20. BCD input 1000 is fed to a 7 segment display through a BCD to 7 segment decoder/driver. The segments which will lit up are ………….

1.     a, b, d

2.     a, b, c

3.     all

4.     a, b, g, c, d

Answer : 3

.

21. A ring counter with 5 flip flops will have ………. states.

1.     5

2.     10

3.     32

4.     Infinite

Answer : 1


23.In the expression A + BC, the total number of minterms will be ………

1.     2

2.     3

3.     4

4.     5

Answer : 4


25. Which of the following is non-saturating?

1.     TTL

2.     CMOS

3.     ECL

4.     Both 1 and 2

 

Answer : 3

26. The number of digits in octal system is ………

1.     8

2.     7

3.     9

4.     10

Answer : 1

27. The access time of a word in 4 MB main memory is 100 ms. The access time of a word in a 32 kb data cache memory is 10 ns. The average data cache bit ratio is 0.95. The efficiency of memory access time is ………

1.     9.5 ns

2.     14.5 ns

3.     20 ns

4.     95 ns

Answer : 2

28. The expression Y = pM (0, 1, 3, 4) is …………..

1.     POS

2.     SOP

3.     Hybrid

4.     none of these

Answer : 1

29.An 8 bit DAC has a full scale output of 2 mA and full scale error of ± 0.5%. If input is 10000000 the range of outputs is ………….

1.     994 to 1014 μA

2.     990 to 1020 μA

3.     800 to 1200 μA

4.     none of the above

Answer : 1

30. Decimal 43 in hexadecimal and BCD number system is respectively……. and …….. 

1.     B2 and 01000011

2.     2B and 01000011

3.     2B and 00110100

4.     B2 and 01000100

Answer : 2

  An AND gate has two inputs A and B and one inhibit input 3, Output is 1 if

1.     A = 1, B = 1, S = 1

2.     A = 1, B = 1, S = 0

3.     A = 1, B = 0, S = 1

4.     A = 1, B = 0, S = 0

Answer: 2

  The greatest negative number which can be stored is 8 bit computer using 2’s complement arithmetic is ……..

1.     -256

2.     -128

3.     -255

4.     -127

Answer: 2

 

A JK flip flop has tpd= 12 ns. The largest modulus of a ripple counter using these flip flops and operating at 10 MHz is ……..

1.     16

2.     64

3.     128

4.     256

Answer: 4

 

The basic storage element in a digital system is ………….

1.     flipflop

2.     counter

3.     multiplexer

4.     encoder

Answer : 1

 

 In a ripple counter,

1.     whenever a flipflop sets to 1, the next higher FF toggles

2.     whenever a flipflop sets to 0, the next higher FF remains unchanged

3.     whenever a flipflop sets to 1, the next higher FF faces race condition

4.     whenever a flipflop sets to 0, the next higher FF faces race condition

Answer : 1

 

 

 

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