DIGITAL ELECTRONICS 100 IMPORTANT MCQ PDF WITH SOLUTION FOR VIZAG MT AND BEL PE EXAM 2017

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

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Attempt Free DIGITAL ELECTRONICS 100 IMPORTANT MCQ Here. Read The Important Electrical MCQ From Below.

Q.1 The NAND gate output will be low if the two inputs are
(A) 00
(B) 01
(C) 10
(D) 11

Ans: D

Q.2  What is the binary equivalent of the decimal number 368
(A) 101110000
(B) 110110000
(C) 111010000
(D) 111100000

Ans: A

Q3.The decimal equivalent of hex number 1A53 is
(A) 6793
(B) 6739
(C) 6973
(D) 6379

Ans: B

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.4  (734)8 = ( )16
(A)    C 1 D
(B) D C 1
(C) 1 C D
(D) 1 D C

Ans: D

Q.5  The number of control lines for a 8 – to – 1 multiplexer is
(A) 2
(B) 3
(C) 4
(D) 5

Ans: B

Q.6   How many Flip-Flops are required for mod–16 counter?
(A) 5
(B) 6
(C) 3
(D) 4

Ans: D

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.7 EPROM contents can be erased by exposing it to
(A) Ultraviolet rays.
(B) Infrared rays.
(C) Burst of microwaves.

Ans: A

Q.8  The hexadecimal number ‘A0’ has the decimal value equivalent to
(A) 80
(B) 256
(C) 100
(D) 160

Ans: D

Q.9  The output of a logic gate is 1 when all its inputs are at logic 0. the gate is either
(A) a NAND or an EX-OR
(B) an OR or an EX-NOR
(C) an AND or an EX-OR
(D) a NOR or an EX-NOR

Ans: D

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.14 Data can be changed from special code to temporal code by using
(A) Shift registers
(B) counters
(C) Combinational circuits
(D) A/D converters.

Ans: A

Q.15 A ring counter consisting of five Flip-Flops will have
(A) 5 states
(B) 10 states
(C) 32 states
(D) Infinite states.

Ans: A

Q.16 The speed of conversion is maximum in
(A) Successive-approximation A/D converter.
(B) Parallel-comparative A/D converter.
(C) Counter ramp A/D converter.
(D) Dual-slope A/D converter.

Ans: B

Q.17 The 2’s complement of the number 1101101 is
(A) 0101110
(B) 0111110
(C) 0110010
(D) 0010011

Ans: D

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.18 The correction to be applied in decimal adder to the generated sum is
(A) 00101
(B) 00110
(C) 01101
(D) 01010

Ans: B

Q.19 When simplified with Boolean Algebra (x + y)(x + z) simplifies to
(A) x
(B) x + x(y + z)
(C) x(1 + yz)
(D) x + yz

Ans: D

Q.20 The gates required to build a half adder are
(A) EX-OR gate and NOR gate
(B) EX-OR gate and OR gate
(C) EX-OR gate and AND gate
(D) Four NAND gates.

Ans: C

Q.21  The code where all successive numbers differ from their preceding number by single bit is
(A) Binary code.
(B) BCD.
(C) Excess – 3.
(D) Gray.

Ans: D

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.22  Which of  the following is the fastest logic
(A) TTL
(B) ECL
(C) CMOS
(D) LSI

Ans: B

Q.23 If the input to T-flipflop is 100 Hz signal, the final output of the three T-flipflops in cascade is
(A) 1000 Hz
(B) 500 Hz
(C) 333 Hz
(D) 12.5 Hz.

Ans: D

Q.24 Which of  the memory is volatile memory
(A) ROM
(B) RAM
(C) PROM
(D) EEPROM

Ans: B

Q.25 -8 is equal to signed binary number
(A) 10001000
(B) 00001000
(C) 10000000
(D) 11000000

Ans: A

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.26 DeMorgan’s first theorem shows the equivalence of
(A)  OR gate and Exclusive OR gate.
(B) NOR gate and Bubbled AND gate.
(C)  NOR gate and NAND gate.
(D)  NAND gate and NOT gate

Ans: B

Q.27 The digital logic family which has the lowest propagation delay time is
(A) ECL
(B) TTL
(C) CMOS
(D) PMOS

Ans: A

Q.28 The device which changes from serial data to parallel data is
(A)  COUNTER
(B) MULTIPLEXER
(C) DEMULTIPLEXER
(D) FLIP-FLOP

Ans: C

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.29 A device which converts BCD to Seven Segment is called
(A) Encoder
(B) Decoder
(C) Multiplexer
(D) Demultiplexer

Ans: B

Q.30 In a JK Flip-Flop, toggle means
(A)  Set Q = 1 and Q = 0.
(B) Set Q = 0 and Q = 1.
(C)  Change the output to the opposite state.
(D)  No change in output.

Ans: C

Q.31 The access time of ROM using bipolar transistors is about
(A) 1 sec
(B) 1 msec
(C) 1 µsec
(D) 1 nsec.

Ans: C

Q.32 The A/D converter whose conversion time is independent of the number of bits is
(A)   Dual slope
(B) Counter type
(C) Parallel conversion
(D) Successive approximation.

Ans:  C

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.33 When signed numbers are used in binary arithmetic, then which one of the following notations would have unique representation for zero.
(A) Sign-magnitude.
(B) 1’s complement.
(C) 2’s complement.
(D) 9’s complement.

Ans: A

Q.38 A 4-bit synchronous counter uses flip-flops with propagation delay times of 15 ns each. The maximum possible time required for change of state will be
(A) 15 ns.
(B)  30 ns.
(C) 45 ns.
(D)  60 ns.

Ans: A

Q.39 Words having 8-bits are to be stored into computer memory. The number of lines required for writing into memory are
(A) 1.
(B) 2.
(C) 4.
(D) 8.

Ans: D

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.40  In successive-approximation A/D converter, offset voltage equal to D/A converter’s output. This is done to
(A) Improve the speed of operation.
(B) Reduce the maximum quantization error.
(C) Increase the number of bits at the output.
(D) Increase the range of input voltage that can be converted.

Ans: B

Q.41 The decimal equivalent of Binary number 11010 is
(A) 26.
(B) 36.
(C)  16.
(D) 23.

Ans: A

Q.42 1’s complement representation of decimal number of -17 by using 8 bit representation is
(A) 1110 1110
(B)  1101 1101
(C) 1100 1100
(D)  0001 0001

Ans: A

Q.43 The excess 3 code of decimal number 26 is
(A) 0100 1001
(B) 01011001
(C) 1000 1001
(D) 01001101

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.44 How many AND gates are required to realize Y = CD+EF+G
(A) 4
(B) 5
(C) 3
(D) 2

Ans: D

Q.45 How many select lines will a 16 to 1 multiplexer will have
(A) 4
(B) 3
(C) 5
(D) 1

Ans: A

Q.46 How many flip flops are required to construct a decade counter
(A) 10
(B) 3
(C) 4
(D) 2

Ans: C

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.47 Which TTL logic gate is used for wired ANDing

(A) Open collector output
(B) Totem Pole
(C) Tri state output
(D) ECL gates

Ans: A

Q.48 CMOS circuits consume power
(A) Equal to TTL
(B) Less than TTL
(C) Twice of TTL
(D) Thrice of TTL

Ans: B

Q.49 In a RAM, information can be stored
(A) By the user, number of times.
(B) By the user, only once.
(C) By the manufacturer, a number of times.
(D) By the manufacturer only once.

Ans: A

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.52  The chief reason why digital computers use complemented subtraction is that it
(A) Simplifies the circuitry.
(B) Is a very simple process.
(C) Can handle negative numbers easily.
(D) Avoids direct subtraction

Ans: C

Q.53 In a positive logic system, logic state 1 corresponds to
(A) positive voltage
(B)  higher voltage level
(C) zero voltage level
(D)  lower voltage level

Ans: B

Q.54 The commercially available 8-input multiplexer integrated circuit in the TTL family is
(A) 7495.
(B) 74153.
(C) 74154.
(D) 74151.

Ans: B

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.55 CMOS circuits are extensively used for ON-chip computers mainly because of their extremely
(A) low power dissipation.
(B) high noise immunity.
(C) large packing density.
(D) low cost.

Ans: C

Q.56 The MSI chip 7474 is
(A) Dual edge triggered JK flip-flop (TTL).
(B) Dual edge triggered D flip-flop (CMOS).
(C) Dual edge triggered D flip-flop (TTL).
(D) Dual edge triggered JK flip-flop (CMOS).

Ans: C

Q.57 Which of the following memories stores the most number of bits
(A) a 5M´ 8 memory.
(B) a 1M ´ 16 memory.
(C) a 5M ´ 4 memory.
(D) a 1M ´12 memory.

Ans: A

Q.58 The process of entering data into a ROM is called
(A) burning in the ROM
(B) programming the ROM
(C) changing the ROM
(D) charging the ROM

Ans: B

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.59 When the set of input data to an even parity generator is 0111, the output will be
(A) 1
(B) 0
(C) Unpredictable
(D)  Depends on the previous input

Ans: B

Q.60 The number 140 in octal is equivalent to
(A)  (96)10 .
(B)  (86)10 .
(C)  (90)10 .
(D)  none of these.

Ans: A

Q.61 The NOR gate output will be low if the two inputs are
(A) 00
(B) 01
(C) 10
(D) 11

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.62 Which of the following is the fastest logic?
(A) ECL
(B) TTL
(C) CMOS
(D) LSI

Ans: A

Q.63 How many flip-flops are required to construct mod 30 counter
(A) 5
(B) 6
(C) 4
(D) 8

Ans: A

Q.64 How many address bits are required to represent a 32 K memory
(A) 10 bits.
(B)  12 bits.
(C) 14 bits.
(D)  16 bits.

Ans: D

Q.65 The number of control lines for 16 to 1 multiplexer is
(A) 2.
(B) 4.
(C) 3.
(D) 5.

Ans: B

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.66  Which of following requires refreshing?
(A) SRAM.
(B) DRAM.
(C) ROM.
(D) EPROM.

Ans: B

Q.67  Shifting a register content to left by one bit position is equivalent to
(A) division by two.
(C) multiplication by two.
(D) subtraction by two.

Ans: C

Q.68 For JK flip flop with J=1, K=0, the output after clock pulse will be
(A) 0.
(B) 1.
(C) high impedance.
(D)  no change.

Ans: B

Q.69 Convert decimal 153 to octal. Equivalent in octal will be
(A)  (231)8 .
(B)  (331)8 .
(C)  (431)8 .
(D)  none of these.

Ans: A

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.70 The decimal equivalent of (1100)2 is
(A) 12
(B) 16
(C) 18
(D) 20

Ans: A

Q.71 The binary equivalent of (FA)16 is
(A) 1010 1111
(B) 1111 1010
(C) 10110011
(D) none of these

Ans: B

Q.72 The output of SR flip flop when S=1, R=0 is
(A) 1
(B) 0
(C) No change
(D) High impedance

Ans: A

Q.73 The number of flip flops contained in IC 7490 is
(A) 2.
(B) 3.
(C) 4.
(D) 10.

Ans: A

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.74 The number of control lines for 32 to 1 multiplexer is
(A) 4.
(B) 5.
(C) 16.
(D) 6.

Ans: B

Q.75 How many two-input AND and OR gates are required to realize Y=CD+EF+G
(A) 2,2.
(B) 2,3.
(C) 3,3.
(D)  none of these.

Ans: A

Q.76 Which of following can not be accessed randomly
(A) DRAM.
(B) SRAM.
(C) ROM.
(D)  Magnetic tape.

Ans: D

Q.77 The excess-3 code of decimal 7 is represented by
(A) 1100.
(B) 1001.
(C) 1011.
(D) 1010.

Ans: D

Q.78 When an input signal A=11001 is applied to a NOT gate serially, its output signal is
(A) 00111.
(B) 00110.
(C) 10101.
(D) 11001.

Ans: B

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

(A) DD.
(B) E0.
(C) F0.
(D) EF.

Ans: B

Q.80 A universal logic gate is one, which can be used to generate any logic function. Which of the following is a universal logic gate?
(A) OR
(B) AND
(C) XOR
(D) NAND

Ans: D

Q.81 The logic 0 level of a CMOS logic device is approximately
(A) 1.2 volts
(B)  0.4 volts
(C) 5 volts
(D)  0 volts

Ans: D

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.82 Karnaugh map is used for the purpose of
(A) Reducing the electronic circuits used.
(B) To map the given Boolean logic function.
(C) To minimize the terms in a Boolean expression.
(D) To maximize the terms of a given a Boolean expression.

Ans: C

Q.83 A full adder logic circuit will have
(A) Two inputs and one output.
(B) Three inputs and three outputs.
(C) Two inputs and two outputs.
(D) Three inputs and two outputs.

Ans: D

Q.84 An eight stage ripple counter uses a flip-flop with propagation delay of 75 nanoseconds. The pulse width of the strobe is 50ns. The frequency of the input signal which can be used for proper operation of the counter is approximately
(A)    1 MHz.
(B)  500 MHz.
(C) 2 MHz.
(D)  4 MHz.

Ans: A

Q.85 The output of a JK flipflop with asynchronous preset and clear inputs is ‘1’. The output can be changed to ‘0’ with one of the following conditions.
(A) By applying J = 0, K = 0 and using a clock.
(B) By applying J = 1, K = 0 and using the clock.
(C) By applying J = 1, K = 1 and using the clock.
(D) By applying a synchronous preset input.

Ans: C

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.86 The information in ROM is stored
(A) By the user any number of times.
(B) By the manufacturer during fabrication of the device.
(C) By the user using ultraviolet light.
(D) By the user once and only once.

Ans: B

Q.87 The conversation speed of an analog to digital converter is maximum with the following technique.

Ans: D

Q.88 A weighted resistor digital to analog converter using N bits requires a total of
(A) N precision resistors.
(B) 2N precision resistors.
(C) N + 1 precision resistors.
(D) N – 1 precision resistors.

Ans: A

Q.89 The 2’s complement of the number 1101110 is
(A) 0010001.
(B) 0010001.
(C) 0010010.
(D) None.

Ans: C

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.90 The decimal equivalent of Binary number 10101 is
(A) 21
(B) 31
(C) 26
(D) 28

Ans: A

Q.91 How many two input AND gates and two input OR gates are required to realize Y = BD+CE+AB
(A) 1, 1
(B)  4, 2
(C) 3, 2
(D)  2, 3

Ans: A

Q.92 How many select lines will a 32:1 multiplexer will have
(A) 5.
(B) 8.
(C) 9.
(D) 11.

Ans: A

DIGITAL ELECTRONICS 100 IMPORTANT MCQ

Q.93 How many address bits are required to represent 4K memory
(A) 5 bits.
(B)  12 bits.
(C) 8 bits.
(D) 10 bits.

Ans: B

Q.94 For JK flipflop J = 0, K=1, the output after clock pulse will be
(A) 1.
(B) no change.
(C) 0.
(D) high impedance.

Ans: C

Q.95 Which of following are known as universal gates
(A) NAND & NOR.
(B)  AND & OR.
(C)  XOR & OR.
(D) None.

Ans: A

Q.96 Which of the following memories stores the most number of bits
(A) 64K ´ 8 memory.
(B) 1M 8 memory.
(C) 32M 8 memory.
(D) 64 ´ 6 memory.

Ans: C

Q.97 Which of following consume minimum power
(A) TTL.
(B) CMOS.
(C) DTL.
(D) RTL.

Ans: B

DIGITAL ELECTRONICS 100 IMPORTANT MCQ