ECE : Digital Electronics - Quiz(MCQ)

A)

Engineering of devices that digital signal

B)

Engineering of devices that produce digital signal

C)

Field of electronics involving the study of digital signal

D)

All of the above

Correct Answer : All of the above

Explanation : Digital electronics is a branch of electronics concerned with the study of digital signals as well as the design of systems that use or generate them. For electronics, gadgets, and equipment, “boolean logic” and “discrete signal electronics” are used.

A)

Open-loop through which electrons can pass

B)

Closed-loop through which electrons can pass

C)

Closed-loop through which Neutrons can pass

D)

None of the above

Correct Answer : Closed-loop through which electrons can pass

Explanation : A circuit is a closed-loop through which electrons can pass. Electrical energy is provided in the circuit by a source of electricity, such as a battery.

A)

Octal

B)

Binary

C)

Hexadecimal

D)

Decimal

Correct Answer : Hexadecimal

Explanation : Hexadecimal is a number system with a base 16. We can divide the word HEXA+DECIMAL for better understanding; it means 6 and 10 make 16. It is the easiest way to write and count numbers represented in terms of base 16. There are sixteen distinct digits in the hexadecimal system, it starts from 0, 1,2,3,4,5,6,7,8,9, A, B, C, D, E and end to F. Where A= 10, B=11, C=12, D=13, E=14, F=15. It is usually represented by 4 bits in binary number system by 8421 code.

A)

It stores digital data on the computer.

B)

It converts electrical power into mechanical power.

C)

It converts alternating current (AC) into direct current (DC).

D)

It takes the digital data from an audio CD and converts it to a useful form.

Correct Answer : It takes the digital data from an audio CD and converts it to a useful form.

Explanation : A "digital-to-analog converter" or DAC refers to an electronic device that converts the digital signals (discrete-time signal) to an analog signal (Continuous-time signal). In other words, we can say that an electronic device converts the signal of 0 and 1 (Binary) into the analog form. For example, the amplitude of the output signal varies according to the input values.

A)

Easier to perform error detection and correction with digital signal

B)

Less susceptible to noise or degradation in quality

C)

Use transistors to create logic gates to perform Boolean logic

D)

All of the above

Correct Answer : Easier to perform error detection and correction with digital signal

Explanation : A digital circuit is a circuit that has a signal that must fall into one of two discrete levels. Each level is read as one of two states (on/off, 0/1, true/false, for example). To perform Boolean logic, digital circuits use transistors to generate logic gates.

A)

2TTL

B)

5TTL

C)

8TTL

D)

10TTL

Correct Answer : 10TTL

A)

OR gate

B)

NAND gate

C)

AND gate

D)

None of the above

Correct Answer : NAND gate

A)

1111

B)

1110

C)

1011

D)

1101

Correct Answer : 1011

Explanation : 1's complement of 0101 is 1010 and 2's complement is 1010+1 = 1011.

A)

is low

B)

is high

C)

is alternately high and low

D)

may be high or low depending on relative magnitude of inputs

Correct Answer : is high

Explanation : In OR any input high means high output.

A)

1010

B)

1110

C)

1000

D)

1001

Correct Answer : 1010

Explanation : 1010 = 8 + 2 = 10 in decimal.

A)

(36.206)â‚ˆ

B)

(36.506)â‚ˆ

C)

(35.506)â‚ˆ

D)

(35.206)â‚ˆ

Correct Answer : (36.206)â‚ˆ

Explanation : If you want to convert a hexadecimal number into an octal number, the first thing you need to do is convert a hexadecimal number into binary form by writing the binary equivalent of each digit in the form of 4 bits. Once you write the number into binary form, you need to group the binary equivalent in 3 bits, then for each of the three bits, the respective digit is written.

(1E.43)â‚â‚† = (0001 1110.0100 0011)â‚‚

= (00011110.01000011)â‚‚

= (011110.010000110)â‚‚

= (011 110.010 000 110)â‚‚

= (36.206)â‚ˆ

A)

6

B)

8

C)

16

D)

32

Correct Answer : 16

Explanation : A NAND gate is a universal logic gate that performs the negation (NOT) of an AND logic operations in digital circuits.

As we know,

Y = 2â¿ Y number of Entries in the truth table

Where,

n = number of inputs.

A)

Computers

B)

Digital cameras

C)

Information appliances

D)

All of the above

Correct Answer : All of the above

Explanation : Computers, information appliances, digital cameras, digital televisions, flash memory, key USB memory, mobile phones, hard discs, and computer memory devices are examples of digital electronics. After analog signals have been transformed to digital form, digital signal processing is applied to them.

A)

Combinational logic circuits

B)

Sequential logic circuits

C)

Both (A) and (B)

D)

None of the above

Correct Answer : None of the above

Explanation : There are two main types of digital logic circuits in digital electronics. They are:

a) Combinational logic circuits

b) Sequential logic circuits

A)

6

B)

32

C)

64

D)

128

Correct Answer : 64

A)

Base 3

B)

Base 6

C)

Base 8

D)

Base 10

Correct Answer : Base 3

A)

encoder

B)

decoder

C)

multiplexer

D)

None of the above

Correct Answer : decoder

Explanation : Decoder converts binary/BCD to alphanumeric.

A)

-31

B)

+37

C)

-27

D)

+27

Correct Answer : -27

Explanation : A = 11100101. Therefore A = 00011010 and A' = A + 1 = 00011011 = 16 + 8 + 2 + 1 = 27. Therefore A = -27.

A)

binary states 0000 to 0011

B)

binary states 1000 to 1111

C)

binary states 1111 to higher

D)

binary states 1010 to 1111

Correct Answer : binary states 1010 to 1111

Explanation : A decade counter counts from 0 to 9. It has 4 flip-flops. The states skipped are 10 to 15 or 1010 to 1111.

A)

5 states

B)

10 states

C)

32 states

D)

Infinite states

Correct Answer : 5 states

A)

2

B)

3

C)

4

D)

5

Correct Answer : 5

Explanation :

The min terms are ABC + ABC + AB C + ABC + ABC.

A)

TTL

B)

ECL

C)

CMOS

D)

Both (A) and (C)

Correct Answer : ECL

Explanation : Since it is non-saturating, ECL has low propagation delay.

A)

8

B)

9

C)

10

D)

12

Correct Answer : 8

Explanation : The octal system has 8 digits 0 to 7.

A)

2 bits

B)

3 bits

C)

4 bits

D)

None of the above

Correct Answer : 4 bits

Explanation : BCD stands for Binary Coded Decimal. It is a type of binary encoding where each decimal digit is represented by a fixed number of bits, usually 4. It is also called 8421 code to represent the maximum number 15. BCD can encode only from 0-9. For example, Decimal number 456, its equivalent BCD code is 0100 0101 0110

A)

(201)â‚â‚€

B)

(202)â‚â‚€

C)

(203)â‚â‚€

D)

(204)â‚â‚€

Correct Answer : (202)â‚â‚€

Explanation : Octal to decimal conversion is usually obtained by multiplying 8 to the power of base along with the value at the index position.

(312)â‚ˆ = 3 * 8² + 1* 8¹ + 2* 8â°

= 192 + 8 +2 = (202)â‚â‚€

A)

High-Threshold Logic

B)

Diode â€“ Transistor Logic

C)

Integrated â€“ injection Logic

D)

Emitter â€“ coupled Logic

Correct Answer : Emitter â€“ coupled Logic

Explanation : Bipolar IC’s can be classified as saturated and non – saturated logic families. ECL (Emitter – coupled Logic) and Schottky TTL are said to come under the non – saturated logic family.

A)

Multi-gate function

B)

Multiple-gate function

C)

Multi-output function

D)

Multiple-output function

Correct Answer : Multi-output function

Explanation : multi-output function is a switching function that will have more than one output. A multiple output gate network will have the digital logic circuit corresponding to the multi-output function.

A)

1 at any input causes the output to be at logic 1

B)

1 at any input causes the output to be at logic 0

C)

0 any input causes the output to be at logic 0

D)

0 at any input causes the output to be at logic 1.

Correct Answer : 1 at any input causes the output to be at logic 1

A)

2â¿

B)

2Â²â¿

C)

2Â²â¿â»Â¹

D)

2â¿â»Â¹

Correct Answer : 2Â²â¿

A)

POS

B)

SOP

C)

Hybrid

D)

None of the above

Correct Answer : POS

A)

B2, 01000011

B)

B2, 01000100

C)

2B, 00110100

D)

2B, 01000011

Correct Answer : 2B, 01000011

Explanation : (43)â‚â‚€ = (2B)â‚â‚†

(43)â‚â‚€ = (01000011)â‚‚

A)

9

B)

12

C)

7

D)

10

Correct Answer : 7

Explanation : ASCII is a 7 bit code.

A)

+ 8

B)

0

C)

-7

D)

- 8

Correct Answer : - 8

Explanation : (a) and (d) both are option, But there is meaning to represent a positive number in 2's complement form, we take complement representation for negative number only. Therefore most appropriate number is "-8".

A)

data bit D is fed to S input and D to R input

B)

data bit D is fed to R input and D to S input

C)

data bit D is fed to both R and S inputs

D)

data bit D is not fed to any input

Correct Answer : data bit D is fed to S input and D to R input

Explaination :

A)

1

B)

2

C)

3

D)

4

Correct Answer : 2

Explanation : 2² = 4. Hence 2 select lines.

A)

2

B)

4

C)

8

D)

12

Correct Answer : 8

Explanation : Total state = 2â¿ = 2â´ = 16

Used state = 2â¿ = 2 x 4 = 8

Unused state = 16 - 8 = 8.

A)

a, b, c

B)

b, c, d

C)

c, d, e

D)

a, b, d

Correct Answer : a, b, c

Explanation :

A)

17

B)

21

C)

37

D)

47

Correct Answer : 37

Explanation : 32 + 4 + 1 = 37 in decimal.

A)

Device with 1 junction

B)

Device with 2 junctions

C)

Device with 3 junctions

D)

Device with 4 junctions

Correct Answer : Device with 2 junctions

Explanation : SCR stands for Silicon Controlled Rectifier; it is a family of thyristors with the same property as thyristors. It is a semiconductor device with three junctions. They are of two types: npnp and pnpn. For the pnpn type, the inner player has a gate terminal, the outer player has an anode terminal, and the outer n layer has a cathode terminal. The SCR controls the flow of anode current once the gate is triggered.

A)

GTO

B)

TRIAC

C)

MOSFET

D)

Thyristor

Correct Answer : MOSFET

Explanation : MOSFET stands for Metal Oxide Semiconductor Field Effects Transistor. It is a semiconductor device that is extensively used for switching and amplifying the signals in digital devices.

The MOSFET is the main part of any integrated circuits, and it can be designed in a single chip because of its small sizes. It is a four-terminal device: source(S), gate(g), drain(d), and body(b).

The body(b) is connected to the source, making MOSFETS a three-terminal device like a field-effect transistor. MOSFETS can be used in both digital and Analog circuits, so it is one of the widely used transistors in digital circuits.

A)

OR, NOT, XOR

B)

XOR, NAND, OR

C)

NOR, NAND, XNOR

D)

NOR, NAND

Correct Answer : NOR, NAND

Explanation : NAND or NOR gates are used to design all other logic gates, so; they are termed universal gates.

A)

111100

B)

010100

C)

000111

D)

101110

Correct Answer : 111100

Explanation : If you want to add any binary number, first, you need to know the binary addition rules.

0 + 1 = 1

1 + 0 = 1

0 + 0 = 0

1 + 1 = 0 (with carry 1)

101001+ 010011 = 111100

A)

Fan â€“ in

B)

Fan â€“ out

C)

Propagation delay

D)

Power dissipation

Correct Answer : Propagation delay

Explanation : Propagation delay represents a function of the switching time of a particular transistor or MOSFET. The propagation delay helps in determining the speed of logic circuits.

A)

When its output impedance is low and the input impedance is low

B)

When its output impedance is high and the input impedance is low

C)

When its output impedance is high and the input impedance is high

D)

When its output impedance is low and the input impedance is high

Correct Answer : When its output impedance is low and the input impedance is high

Explanation : When the output impedance of a logic gate is low and its input impedance is high, then one logic gate can drive many other logic gates. High impedance in the output will resist the driving of many logic gates.

A)

Serial adder

B)

Ripple â€“ carry adder

C)

Full â€“ adder

D)

Half â€“ adder

Correct Answer : Ripple â€“ carry adder

Explanation : A Ripple – carry adder is a parallel binary adder in which the addition of more than 1 – bit data can be done simultaneously. The inputs to a parallel circuit can be sent and processed at once unlike series circuits in which inputs are sent one by one.

A)

State Reduction

B)

State Assignment

C)

State Evaluation

D)

State Minimization

Correct Answer : State Assignment

A)

logic 0 voltage level is lower than logic 1 voltage level.

B)

logic 0 voltage level is higher than logic 1 voltage level

C)

logic 0 and 1 are represented by 0 and positive voltage respectively

D)

logic 0 and, -1 are represented by negative and positive voltages respectively

Correct Answer : logic 0 voltage level is lower than logic 1 voltage level.

A)

OR gates

B)

NOT gates

C)

NAND gates

D)

None of the above

Correct Answer : NAND gates

A)

Each hexadecimal digit can be represented as a sequence of three binary symbols

B)

In a positional number system, each symbol represents the same value irrespective of its position

C)

It is not always possible to find the exact binary

D)

The highest symbol in a position number system as a value equal to the number of symbols in the system

Correct Answer : It is not always possible to find the exact binary

A)

2 cells

B)

4 cells

C)

8 cells

D)

16 cells

Correct Answer : 16 cells

Explanation : 2â´= 16.

A)

1

B)

2

C)

4

D)

8

Correct Answer : 1

Explanation : In a parallel in register only one pulse is needed to enter data.

A)

From left to right

B)

From right to left

C)

Both from left to right and right to left

D)

None of the above

Correct Answer : Both from left to right and right to left

A)

F 8

B)

E 8

C)

F 9

D)

E 9

Correct Answer : E 8

Explanation : 11 01000 = 128 + 64 + 32 + 8 = 232 in decimal = E 8 in hexadecimal.

A)

A234Fâ‚â‚†

B)

C47BEâ‚â‚†

C)

A1111â‚â‚†

D)

C47BBâ‚â‚†

Correct Answer : C47BEâ‚â‚†

Explanation : Convert to decimal, add and change the result to hexadecimal.

A)

Flip flop only

B)

Latch only

C)

Both latch and flip flop

D)

None of the above

Correct Answer : Flip flop only

Explanation : This the main difference between latch and flip-flop. Only flip-flop has clock input.

A)

from 0 to 4

B)

from 0 to 3

C)

from any number n to n + 4

D)

None of the above

Correct Answer : from 0 to 3

Explanation : Mod 4 counter has 4 states, 0 to 3.

A)

TTL

B)

ECL

C)

CMOS

D)

None of the above

Correct Answer : CMOS

Explanation : Because of low power consumption CMOS is used in pocket calculators.

A)

5

B)

8

C)

9

D)

10

Correct Answer : 10

Explanation : 12 in octal = 8 + 2, i.e., 10 in decimal.

A)

0111 1001

B)

1000 1001

C)

0111 1111

D)

1000 1111

Correct Answer : 0111 1001

Explanation : Decimal 46 in excess 3 code = 46 + 33 = 79 in decimal = 0111 1001 in 4 bit binary.

A)

4 switches in parallel

B)

4 switches in series

C)

2 switches in series and 2 in parallel

D)

three switches in parallel and one in series

Correct Answer : 4 switches in series

Explanation : All the switches have to be closed so that the circuit can be made. In AND gate all the inputs have to be high for output to be high.

A)

full adder

B)

shift register

C)

decade counter

D)

full subtractor

Correct Answer : full subtractor

Explaination :

A)

2

B)

3

C)

7

D)

8

Correct Answer : 7

Explanation : Number of comparators = 2â¿ - 1 = 2³ - 1 = 7.

A)

1

B)

32

C)

120

D)

256

Correct Answer : 256

Explanation : 2â¸ = 256.

A)

8

B)

10

C)

100

D)

None of the above

Correct Answer : 10

Explanation : 4/0.4 = 10

A)

85

B)

95

C)

105

D)

115

Correct Answer : 85

Explanation : 01010101 in binary and 64 + 16 + 4 + 1 = 85 in decimal.

A)

4

B)

8

C)

16

D)

32

Correct Answer : 16

Explanation : 2â´ = 16.

A)

000 to 111

B)

111 to 000

C)

000 to 111 and also from 111 to 000

D)

None of the above

Correct Answer : 000 to 111 and also from 111 to 000

Explanation : Since it is an up-down counter it can count upwards or downwards.

A)

0 to 131071

B)

0 to 65535

C)

0 to 4093

D)

0 to 1023

Correct Answer : 0 to 65535

Explanation : IC 74193 is a divide by 16 counter.

Since 4 stages are used, counting range = 16â´ = 65536.

A)

The two unused inputs are left open

B)

The two unused inputs are left 0

C)

The two unused inputs are connected to 0

D)

The two unused inputs are connected to 1

Correct Answer : The two unused inputs are connected to 1

Explanation : Unused inputs should be given high input.

A)

the same as static RAM

B)

less than that of static RAM

C)

more than that of static RAM

D)

either equal or less than that of static RAM

Correct Answer : more than that of static RAM

Explanation : Dynamic RAM has higher packing density and requires lesser space.

A)

8

B)

12

C)

24

D)

32

Correct Answer : 32

Explanation : (1024 x 8)/(256 x 1 ) = 32.

A)

SOP

B)

POS

C)

Hybrid

D)

None of the above

Correct Answer : SOP

Explanation : It is sum of products.

73 .

A)

EEPROM

B)

UVPROM

C)

Both UVPROM and EEPROM

D)

None of the above

Correct Answer : Both UVPROM and EEPROM

Explanation : Both ultra violet and electric pulses are used for erasing.

A)

to match output conditions of driver with input conditions of load device

B)

to match output conditions of load device with input conditions of driver

C)

Both (A) and (B)

D)

Neither (A) nor (B)

Correct Answer : to match output conditions of driver with input conditions of load device

Explanation : Output of driver stage has to be matched with input of load.

A)

ACBâ‚â‚†

B)

ECDâ‚â‚†

C)

ACAâ‚â‚†

D)

AAAâ‚â‚†

Correct Answer : ECDâ‚â‚†

Explaination : Convert to decimal, subtract and change the result to hexadecimal.

A)

16

B)

256

C)

1024 (1 K)

D)

64K (64 x 1024)

Correct Answer : 64K (64 x 1024)

Explanation :

2^{24} = 2^{16}.

77 .

A)

A

B)

A . B + C

C)

A . B + A . C

D)

(A + B) . (A + C)

Correct Answer : (A + B) . (A + C)

Explanation : This is distributive law.

A)

101

B)

1101

C)

1110

D)

1111

Correct Answer : 1101

Explaination : Rules for binary addition.

0 + 0 = 0

0 + 1 = 1 + 0 = 1

1 + 1 = 10

i.e., 1 + 1 equals 0 with a carry of 1 to next higher column. 1 + 1 + 1 = 11

i.e., 1 + 1 + 1 equals 1 with a carry of 1 to next higher column.

A)

2

B)

18

C)

2 or 18

D)

2 or 18 or 34

Correct Answer : 2 or 18 or 34

Explanation : At pulse 1 the state changes to 0001 and at pulse 2 it changes to 0010 Since it has a total of 16 states, the counter returns to 0000 after 16 and 32 pulses.

A)

239

B)

240

C)

255

D)

256

Correct Answer : 255

Explanation : FF = 15 x 16 + 15 = 255.

A)

1024

B)

2048

C)

4096

D)

16384

Correct Answer : 16384

Explanation : 2¹â´ = 16384.

A)

125

B)

125 x 10³

C)

125 x 10â¶

D)

None of the above

Correct Answer : 125 x 10³

A)

10 mV

B)

8 V

C)

0.82 V

D)

0.1 V

Correct Answer : 0.82 V

Explanation : Output for decimal input 82/(10000010) = 0.01 x 82 = 0.82 V.

A)

010011

B)

100110

C)

011001

D)

010010

Correct Answer : 010011

Explanation : If you want to subtract any binary number, first, you need to know the binary subtraction rules.

1 - 0 = 1

0 - 1 = 1 (With borrow 1)

0 - 0 = 0

1 - 1 = 0

therefore, the subtraction of 101001 - 010110 = 010011

A)

011011000

B)

011011100

C)

011100011

D)

011001100

Correct Answer : 011011100

Explanation : If you want to multiply any binary number, you need to know the binary multiplication rules.

1 * 0 = 0

0 * 1 = 0

0 * 0 = 0

1 * 1 = 1

therefore, the multiplication of 10100 - 01011 = 011011100

A)

0101

B)

1010

C)

0011

D)

0110

Correct Answer : 0101

Explanation : If you want to divide any binary number, you need to know the binary division rule. The binary division is accomplished using the long division rule.

Therefore, the remainder of 111001 ÷ 1101 = 0101

A)

Two 3 input OR gates

B)

Two 2 input OR gates

C)

Two 3 input AND gates

D)

Two 2 input AND gates

Correct Answer : Two 2 input AND gates

Explanation : Two 2 input AND gates are placed with a NOR – based S – R latch to convert it to an S – R flip – flop. One AND gate is given R in one input and clock in the other. Similarly the second AND gate is given S in one input and clock in the other.

A)

When the inputs are all zero

B)

When the inputs are all one

C)

When the clock is negative

D)

When the clock is positive

Correct Answer : When the clock is negative

Explanation : A negative level triggered flip – flop has a NOT gate present between clock input and the input of AND gate. Thus, the negative level triggered flip – flop change its state when the clock is negative.

A)

S

B)

R

C)

Clock

D)

Both S and R

Correct Answer : Both S and R

Explanation : The input for which the flip flop changes its state when synchronized with the clock is called the synchronous control inputs. For the S – R flip flop, both S and R are synchronous control inputs.

A)

A & B

B)

B & C

C)

A & D

D)

C & D

Correct Answer : A & B

A)

A bistable MV

B)

A latch

C)

An astable MV

D)

A monostable MV

Correct Answer : A latch

A)

NOT gate

B)

OR gate

C)

AND gate

D)

None of the above

Correct Answer : NOT gate

A)

12.5 MHz

B)

6.25 MHz

C)

3.25 MHz

D)

1.25 MHz

Correct Answer : 6.25 MHz

Explaination :

A)

B)

0.1 V

C)

0.9 V

D)

0.99 V

Correct Answer : 0.99 V

Explaination :

A)

00110

B)

11000

C)

01000

D)

10110

Correct Answer : 11000

Explanation : Decimal 8 = 1000 and - 8 = 11000.

A)

2 and 1

B)

2 and 2

C)

3 and 2

D)

3 and 3

Correct Answer : 3 and 2

Explanation :

A)

8

B)

10

C)

15

D)

16

Correct Answer : 16

A)

A = B = C = 0

B)

A = B = C = 1

C)

A = B = 1 and C = 0

D)

A = C = 1 and B = 0

Correct Answer : A = B = C = 0

Explanation : NOR gate gives High output when all inputs are Low.

A)

J = 0, K = 1

B)

J = 1, K = 1

C)

J = 0, K = 0

D)

J = 1, K = 0

Correct Answer : J = 1, K = 1

Explanation : Toggling means switching between the two states when output changes to its complement on applying clock signal. For example, suppose you assume the initial output to be X (1 or 0), then after toggling, the output state will be X' (0 or 1, respectively). Both j and k should be 1 for toggle in JK flip flop.

A)

SSI

B)

LSI

C)

MSI

D)

VLSI

Correct Answer : MSI

Explanation : The terminologies like MSI, SSI, LSI and VLSI came out from the complexity of the integrated circuit. It means the total number of transistors are fabricated on a single chip. Jack Kilby invented the first integrated circuit in 1959, so, after that, the Integrated circuit has emerged like SSI, LSI, MSI and VLSI.

In MSI (Medium Scale Integration) = 30 - 300 gates /chip (counters, multiplexers, registers)

In LSI (Large Scale Integration) = 300 - 3000 gates /chip (8-bit processors)

In SSI (Small-Scale Integration) = 3 - 30 gates /chip (logic gates, flip flops)

In VLSI (Very Large-Scale Integration) = >3000 gates / chip (16 bit and 32- bit processors)

A)

Power Inverter

B)

Voltage source Inverter

C)

Current source Inverter

D)

Both (B) and (C)

Correct Answer : Both (B) and (C)

Explanation : Inverter refers to an electronic device that converts direct current (DC) to alternating current (AC). It has a wide range of applications for small appliances, TVs, DVD players, computer power supply to large electric power supply like photovoltaic solar cells.

Based on the type of the input source, Inverters are divided into two categories.**Current source inverters :** In current source inverters, the input is a current source.**Voltage source inverters :** In voltage source inverters, the input is a voltage source.

A)

0

B)

1

C)

Clock

D)

None of the above

Correct Answer : Clock

Explanation : A clock must be used along with synchronous control inputs to trigger a change in the flip flop. These flip – flops may be edge – triggered or level – triggered. A change should occur only when the clock changes from 0 to 1 or vice versa.

A)

Fan â€“ in

B)

Fan â€“ out

C)

Propagation delay

D)

Noise immunity

Correct Answer : Fan â€“ in

Explanation : The TTL circuit uses multi – emitter transistors with many emitters in the input. Thus, the number of emitters is determined by the fan – in. Fan – in determines the number of inputs the particular gate can handle.

A)

No change

B)

0

C)

1

D)

Toggle between 0 and 1

Correct Answer : No change

Explanation : When the clock is low, the input given to D will have no effect. This is because the set and reset pins of the NAND gates are kept high. When HIGH value is given to NAND gates the output result will be zero.

A)

It is slower than software

B)

Floating point hardware is costly

C)

Of no specific reason

D)

It is not possible to perform floating point addition by hardware

Correct Answer : Floating point hardware is costly

A)

Input operation

B)

Tristate output operation

C)

Bi-directional I/O pin access

D)

All of the above

Correct Answer : All of the above

A)

12

B)

19

C)

21

D)

27

Correct Answer : 21

A)

1011

B)

1110

C)

1100

D)

1010

Correct Answer : 1110

Explanation :

A = 1110,

A = 0001,

A + 1 = 0001 + 1 = 0010 = 2

Therefore A = -2.

A)

Analog quantity

B)

Digital quantity

C)

Either Analog or Digital quantity

D)

None of the above

Correct Answer : Analog quantity

Explanation : Temperature variation is continuous with respect to time. So, it is an analog quantity.

A)

0101100

B)

0100111

C)

0100110

D)

0110110

Correct Answer : 0100110

Explanation : If you want to calculate 1's complement of any binary number, you need to reverse its binary bits. All the 0's to 1's and 1's to 0's.

Therefore, 1's complement of 1011001 = 0100110

A)

0100011

B)

0100011

C)

0110101

D)

0100101

Correct Answer : 0100101

Explanation : If you want to calculate 2's complement of any binary number, first you need to calculate 1's complement of that number and then add 1 to it.

2's complement of 1011011 = 0100100 + 1 = 0100101.

A)

AND and OR

B)

NAND and NOR

C)

AND and NOR

D)

NAND and OR

Correct Answer : NAND and NOR

Explanation : The MOS logic family uses the MOSFET devices to perform its operation. NAND and NOR are the basic gates that are the building blocks of most digital circuits.

A)

Acts as a current source

B)

Acts as a current sink

C)

Acts as a voltage sink

D)

Acts as a voltage source

Correct Answer : Acts as a current source

Explanation : If the gate output is high in a TTL circuit, the current must be given to the input of the gate being driven. Thus, the output must act as a current source. In a normal TTL circuit, about 40μA of current is drawn from the input from a output that is HIGH.

A)

12 CPS

B)

10 CPS

C)

120 CPS

D)

None of the above

Correct Answer : 12 CPS

A)

All the inputs are â€˜0â€™

B)

Either of the inputs is â€œ1â€

C)

All the inputs to the gates are â€œ1â€

D)

All the inputs and outputs are complemente'

Correct Answer : All the inputs and outputs are complemente'

A)

QFP

B)

PGA

C)

BGA

D)

PLCC

Correct Answer : BGA

A)

Hardware problem

B)

Software problem

C)

User input problem

D)

Input-Output problem

Correct Answer : Software problem

Explanation : An overflow is a software problem that takes place when the processor cannot respond to the output accurately when it gives an out-of-range result.

A)

Flip-flop

B)

Register

C)

NOR gate

D)

XOR gate

Correct Answer : Flip-flop

Explanation : A flip-flop refers to an electronic circuit with two stable states that can be used to store the binary data (1,0). Flip-flop can store only one bit of data, either a logic 1 or 0. This logic state can be represented as the voltage on the flip-flop's output because it can be controlled to hold the logic state, effectively a 1 -bit memory.

A)

100010110111

B)

100001110111

C)

100010010110

D)

100001010110

Correct Answer : 100010110111

Explanation : If you want to calculate the excess-3 code of any number, you need to add "3" to each digit of the same number. In the above problem, the addition of "3" to each digit gives you a new digit "8," "11," and "7." Hence, according to 8421 rules, the corresponding four-bit binary equivalents are 100010110111

A)

1

B)

2

C)

3

D)

4

Correct Answer : 4

Explanation : According to Hamming’s analysis, a minimum distance of 2 is required for single error detection. This Hamming distance represents the number of bits that are changed from one code word to the other.

A)

Parity method

B)

Odd-Even method

C)

Check sum method

D)

Bit generation method

Correct Answer : Check sum method

Explanation : Check sum enables to find double errors and also find the erroneous bits. The parity method can help in finding only single errors within a word as a double error will not change the parity bits.

A)

Low inductance

B)

Low capacitance

C)

High inductance

D)

High capacitance

Correct Answer : Low capacitance

Explanation : TTL circuit uses multi – emitter transistors which have a smaller area. The capacitance can be represented in terms of area and distance between the plates using the expressions C = Aε0/d. As “C” is directly proportional to “A”, a smaller area leads to a lower capacitance.

A)

0

B)

1

C)

Either 0 or 1

D)

Any number except 0 and 1

Correct Answer : Either 0 or 1

Explanation : A don’t care condition can take 0 or 1 according to the requirement. SOP expressions may consider it to be 1 to increase the number of 1s and POS expressions may consider it to be 0 to increase the number of 0s.

A)

ECL

B)

CMOS

C)

TTLLS

D)

TTLAS

Correct Answer : ECL

A)

OR operation

B)

NOT operation

C)

AND operation

D)

None of the above

Correct Answer : NOT operation

A)

G52F

B)

F53F

C)

F52E

D)

F53O

Correct Answer : F53O

A)

10101.001

B)

10101.010

C)

10100.111

D)

10100.001

Correct Answer : 10101.001

A)

It is used by everybody

B)

Many digital computers use NAND gates.

C)

Any logic function can be realized by NAND gates alone

D)

All the minization techniques are applicable for optimum NAND gate realization

Correct Answer : Any logic function can be realized by NAND gates alone

A)

Distributive properties

B)

Associative properties

C)

Commutative properties

D)

All of the above

Correct Answer : All of the above

Explanation : In Boolean algebra, the distributive properties are given by the following equation:**A + BC = (A+B) (A+C) & A(B+C) = AB+AC**

In Boolean algebra, the commutative properties are given by the following equation:

In Boolean algebra, the distributive properties are given by the following equation:

A)

FILO memory

B)

FIFO memory

C)

Flash memory

D)

None of the above

Correct Answer : FIFO memory

Explanation : FIFO stands for First In - First Out. The queue is a type of memory based on FIFO, which means the request which has come first will be dealt with first. For example, the line of a crowd for booking railway tickets. The person who came first will get the ticket first. In the case of a Queue data structure, we call an ordinary queue as a FIFO queue.

A)

600

B)

900

C)

1200

D)

1800

Correct Answer : 1200

Explanation : Mainly, there are two types of 3 phase rectifiers: A half-wave rectifier and a full-wave rectifier. Many industries work on 3 phase power supply instead of a single phase. In three-phase half-wave rectifiers, each diode conducts for a duration of 120 0 because the cycle will be repeated itself, and each thyristor conducts for 1200 duration when the firing angle is less than 300.

A)

(AB)' = A' + B'

B)

(A+B)' = A'*B

C)

(AB)' = A + B

D)

(AB)' = A' + B

Correct Answer : (AB)' = A' + B'

Explanation : DeMorgan's theorems play a vital role in digital electronics. It gives an equivalency between the logic gates. There are two distinct types of DeMorgan's theorems: the first gives the equivalent of the NAND gate, and the other gives the equivalent of the NOR gate. As per the dual property of DeMorgan's theorem (AB)' = A' + B' & (A+B) = A' * B'

A)

SOP

B)

POS

C)

OR operation

D)

NAND operation

Correct Answer : SOP

Explanation : SOP stands for "Sum of products." SOP is a way that a Boolean Algebra formula can be written. For example, the sum of product formula: AB + A'B'. In other words, it is defined as the logical sum of two or more logical product terms. POS refers to the logical product of two or more than two logical sum terms.

A)

Pair

B)

Octet

C)

Octave

D)

Quad

Correct Answer : Quad

Explanation : A group of 1s in 4 cells of a K – map is called Quad. A group of 1s in 2 cells of a K – map is called Pair and a group of 1s in 8 cells of a K – map is called Octet.

A)

Twice the frequency of clock input

B)

Half the frequency of clock input

C)

Equal to the frequency of clock input

D)

Independent of the frequency of clock input

Correct Answer : Half the frequency of clock input

Explanation : A single flip flop is a divide – by – two device. The frequency of the output from a JK flip – flop, when J = 1, K = 1, and a clock with pulse waveform is given is half the frequency of clock input.

A)

Buffer

B)

NOT gate

C)

NOR gate

D)

NAND gate

Correct Answer : NOR gate

Explanation : The negative level triggered the flip – flop in Digital Electronics changes its state when the clock is negative. Thus, a negative level triggered flip – flop has a NOT gate present between clock input and the input of AND gate.

A)

0

B)

1

C)

T

D)

Clock

Correct Answer : T

Explanation : The input at which the flip flop changes its state when synchronized with the clock is called the synchronous control inputs. For T flip flop T is the synchronous control input.

A)

Can be used to make any gate

B)

have lower fabrication area

C)

consume least electronic power

D)

provide maximum density in a chip.

Correct Answer : Can be used to make any gate

A)

(00, 10, 01, 11)

B)

(00, 10, 11, 01)

C)

(00, 01, 10, 11)

D)

(00, 01, 11, 10)

Correct Answer : (00, 01, 11, 10)

A)

OR gate

B)

NOT gate

C)

AND gate

D)

None of the above

Correct Answer : NOT gate

A)

Less expensive

B)

Easier to maintain

C)

Always more accurate and faster

D)

Useful over wider ranges of problem types

Correct Answer : Useful over wider ranges of problem types

A)

Cycle diagram

B)

Block diagram

C)

Venn diagram

D)

Square diagram

Correct Answer : Venn diagram

Explanation : K- Map, also known as Karnaugh map, refers to a pictorial representation of a truth table. It helps in minimizing variables of any Boolean expression. It is also an abstract form of a Venn diagram arranged as a square of a matrix, where each square represents a minterm or maxterm.

A)

FET

B)

SCR

C)

PNP transistor

D)

NPN transistor

Correct Answer : SCR

Explanation : SCR stands for silicon-controlled rectifiers. SCR is used in speed control DC motor. SCR is controlled by a variable resistor potentiometer. Many Industries use variable speed drives for industrial applications. For example, rolling mills, railway traction, etc.

A)

2

B)

4

C)

8

D)

12

Correct Answer : 4

Explanation : In digital electronics, the smallest unit of storage consisting of either 0 or 1 is called a bit. The arrangement of such 4 bits is known as a nibble. The arrangement of such 8 bits is known as a byte.

A)

A = 0, B = 0

B)

A = 0, B' = 1

C)

A = 0, B = 1

D)

A = 1, B = 1

Correct Answer : A = 0, B = 0

Explanation : An XNOR refers to a digital logic gate with two or more inputs and one output that executes logical equality. The output of an XNOR gate is true either all of its inputs are true, or all of its inputs are false. When one of its inputs is false, and others are true, then the output is false. The output of the XNOR gate is given by the following equation.

AB + A'B,' For A = 0 AND B = 0 the output will be 1.

A)

Smaller area

B)

Larger area

C)

Smaller resistance

D)

Larger resistance

Correct Answer : Smaller area

Explanation : TTL circuit uses multi – emitter transistors. These transistors have a smaller area. As Capacitance is directly proportional to area, a smaller area leads to a lower capacitance.

A)

Acts as a voltage source

B)

Acts as a current source

C)

Acts as a voltage sink

D)

Acts as a current sink

Correct Answer : Acts as a current sink

Explanation : If the gate output is Low in a TTL digital circuit, the gate must be capable of sinking current drawn from the input of gates. Thus, the output must act as a current sink.

A)

Two 8 x 1 mux

B)

Three 8 x 1 mux

C)

Two 16 x 1 mux

D)

Three 16 x 1 mux

Correct Answer : Two 16 x 1 mux

Explanation : Two 16 x 1 mux will enable to give 32 inputs. The final output can be obtained after passing the output from each 16 x 1 mux through an OR gate. The select lines will help in selecting a particular output.

A)

J.Q

B)

K.Q

C)

J.K.Q

D)

None of the above

Correct Answer : K.Q

Explanation : In Digital Electronics, to convert SR flip – flop to JK flip – flop the “R” input in the SR flip – flop is given input “K” and “Q” through an AND gate. The truth table of SR flip – flop and JK flip – flop are combined to get the expression.

A)

1

B)

2

C)

3

D)

4

Correct Answer : 3

Explanation : According to Hamming’s analysis, a minimum distance of 3 is required for a single error correction. Hamming distance represents the number of bits that change from one code word to the other.

A)

Single error

B)

Double error

C)

Triple error

D)

Multiple errors

Correct Answer : Single error

Explanation : The parity method can help in finding only single errors within a word. The double errors cannot be found as the parity of the bits does not change. If double errors need to be identified, the check – sum method can be used.

A)

Two’s complement only

B)

Sign and magnitude and one’s complement only

C)

Two’s complement and one’s complement only

D)

All three representations

Correct Answer : All three representations

A)

Algebraic code

B)

Weighted code

C)

Cyclic redundancy code

D)

Self-complementing code

Correct Answer : Self-complementing code

A)

FFFF (hex)

B)

1111 (binary)

C)

7777 (octal)

D)

All of the above

Correct Answer : All of the above

A)

Stop signal

B)

Invert input signal

C)

Act as a universal gate

D)

None of the above

Correct Answer : Invert input signal

A)

Inductor

B)

Transistor

C)

Diode

D)

Transformer

Correct Answer : Diode

Explanation : DTL stands for Diode Transistor Logic, where the diode serves as the Input network, and the switching operation is performed by the transistor. DTL is a predecessor of TTL (Transistor-Transistor Logic). The logic functions can be performed using resistors for biasing, transistors to amplify and diodes to switch and isolate inputs, producing logic levels.

A)

Intersection

B)

Union

C)

Division

D)

Both (B) and (C)

Correct Answer : Intersection

Explanation : AND operation is equivalent to Intersection. It means Y = A.B i.e. A AND B = A Intersection B. The output is 1, if and only if all the given inputs are 1.

A)

Resistors only

B)

BJT (Bipolar Junction Transistors) only

C)

JEFT only

D)

Both (A) and (B)

Correct Answer : Both (A) and (B)

Explanation : TTL stands for Transistor-Transistor logic. It is a class of type of digital circuits made up of bipolar junction transistors and resistors. BJT has two types of charge carriers: the first one is the electron and the holes. There are two types of BJTs: NPN and PNP. In TTL, resistors play a very short role, and both logic gating and amplifying functions are carried out by the transistors.

A)

ECL

B)

DTL

C)

TTL

D)

CMOS

Correct Answer : ECL

Explanation : ECL stands for Emitter Coupled Logic. It is the fastest of all the logic families because of its higher transmission rate.**In Emitter Coupled Logic,**

***** The storage time is removed as the transistors are utilized in different amplifier mode and are never driven into saturation.

***** It is the fastest logic family and has the minimum propagation delay.**In CMOS logic,**

***** Power dissipation is basically 10nw per gate, relying on the power supply voltage, output load etc.

***** The CMOS components are usually expensive, but CMOS technology is cost-efficient.

***** It has high input impedance.**In TTL,**

***** Power dissipation is basically 10nw per gate.

***** Cost-efficient components.

***** The possibility of damage to the equipment is less from electrostatic charge as compared to CMOS.

A)

Signed numbers

B)

Unsigned numbers

C)

Both (A) and (B)

D)

None of the above

Correct Answer : Unsigned numbers

Explanation : The negative integers are represented by signed numbers on the extreme left side, whereas the positive integers are represented using unsigned numbers.

A)

D â€“ flip flop

B)

SR flip â€“ flop

C)

T flip â€“ flop

D)

JK flip â€“ flop

Correct Answer : T flip â€“ flop

Explanation : SR, D, and JK flip flops can be used to construct a serial shift register. A T flip – flop gives the output 0 when input 1 is given and gives output 1 when input 0 is given. Thus, it cannot be used as a serial shift register.

A)

High threshold logic

B)

Emitter â€“ Coupled Logic

C)

Merged Transistor Logic

D)

Resistor â€“ Transistor logic

Correct Answer : Merged Transistor Logic

Explanation : Inter – Integrated circuits can be represented by IIC or I2C is also called the Merged Transistor Logic. They use n – p – n or p – n – p transistors to form IC’s.

A)

ECL

B)

IIC

C)

TTL

D)

RTL

Correct Answer : ECL

Explanation : Emitter coupled logic or ECL is a Current – Mode logic. While operating in active mode, they help in eliminating the turn – off delay of saturated transistors. ECL family has a higher switching speed and dissipates more power.

A)

Two 2 â€“ input AND gates

B)

Four 2 â€“ input AND gates

C)

Eight 2 â€“ input AND gates

D)

Sixteen 2 â€“ input AND gates

Correct Answer : Sixteen 2 â€“ input AND gates

Explanation : Four 4 – bit parallel binary adders along with 16 number of 2 – input AND gates will be required to construct a 4 – bit parallel multiplier. The AND gate helps in getting the partial products while the parallel – adder are used to add the partial products.

A)

OR gate

B)

NAND gate

C)

NOT gate

D)

EXCLUSIVE OR gate

Correct Answer : EXCLUSIVE OR gate

A)

0

B)

1

C)

Either 0 & 1

D)

None of the above

Correct Answer : 0

A)

1000

B)

1024

C)

1064

D)

1099

Correct Answer : 1024

A)

6 flip flops

B)

6 flip flops and 2 AND gates

C)

6 flip flops and 4 AND gates

D)

None of the above

Correct Answer : 6 flip flops and 4 AND gates

Explanation : 2^{6} = 64

So we need 6 flip-flops and (6 - 2) = 4 AND gates.

A)

4

B)

6

C)

8

D)

10

Correct Answer : 4

Explanation : 2^{4} = 16

A)

4 and 6 respectively

B)

5 and 7 respectively

C)

6 and 4 respectively

D)

7 and 5 respectively

Correct Answer : 6 and 4 respectively

Explanation : 2^{6} = 64 Hence 6 flip-flops. The number of AND gates is 6 - 2 = 4 see in the given figure

A)

4.5 V

B)

3.0 V

C)

2.0 V

D)

1.5 V

Correct Answer : 3.0 V

Explanation :

A)

DC motors

B)

Universal motors

C)

Induction motors

D)

Three-phase AC motors

Correct Answer : DC motors

Explanation : The Ward Leonard system was implemented and used to control the speed of DC shunt electric motors. Previously, it was quite convenient to obtain a variety of speeds and reversing for industrial applications. The system consisted of any prime mover, including an AC motor driving a DC shunt generator. The armature of the DC generator was directly connected to the shunt motor's armature to be controlled. The DC motor had its magnetic field continuously excited while that of the DC generator, the magnetic field could be controlled in intensity and direction. As the prime mover rotated, the field of the DC generator was adjusted as required, hence its armature current-controlled, this current would be adjusted in magnitude and direction, and this, being fed to the armature of the DC motor, would create a driving torque as it reacted with the continuously applied motor field.

A)

The diode behaves like a thyristor.

B)

The diode behaves like a resistor.

C)

The diode is destroyed.

D)

The diode behaves like a tunnel diode.

Correct Answer : The diode is destroyed.

Explanation : PIV stands for Peak Inverse Voltage. In other words, PIV is defined as the maximum voltage that can apply to a diode in the reverse direction. Applying higher voltage will cause the diode to destroy. Start conducting current in the normally "OFF" direction, which will damage the diode and often do things you don't like to your circuit. The exact details depend on the circuit design.

We usually select the PIV larger than the largest normal reverse operating voltage in our circuit. If you are making a full-wave rectifier for 220 Vac, you'd typically select a diode with a 240 or more PIV to give some "head room" and "safety factor" on the diode. The minimum should usually be selected like this: round-up from your designed or simulated reverse voltage to the next higher PIV for a diode family that gives you the current you require.

A)

Silicon Nitride

B)

Copper sulphate

C)

Aluminum sulphate

D)

Silicon dioxide

Correct Answer : Silicon dioxide

Explanation : A MOSFET is a field-effect transistor. It depends on the presence of an electric field to control the characteristics of the conductive channel. In the MOSFET, the gate is insulated from the substrate by a layer of silicon dioxide, which is basically glass. The charges accumulate on the gate to create the electric field instead of just having them flow out. So, while silicon is the main constituent of the conductive channel, a thin layer of silicon dioxide is used to insulate the gate.

175 .

A)

Microprocessor

B)

Digital logic

C)

Inverter

D)

Both (A) and (B)

Correct Answer : Both (A) and (B)

Explanation : CMOS stands for Complimentary Metal Oxide Semiconductor. It is a type of (mostly) digital logic that uses a pair of complementary field-effect transistors to switch electric current. There are some analog CMOS devices; they are a lot less common. CMOS technology is used in many electronic devices like Microprocessor, Ram, Microcontroller, and other logic circuits. When the gate is ON, one transistor is on, and the other is off. When the gate is OFF, the first transistor is off, and the other is ON.

A)

1

B)

2

C)

4

D)

8

Correct Answer : 4

Explanation : In Digital Electronics, 4 cycles of addition and shifting in a 4 – bit multiplier are required to perform multiplication using the shift method. The multiplicand is copied as a partial product when multiplier bit is 1 and multiplicand is 0 when multiplier bit is 0.

A)

8421 code

B)

5421 code

C)

2441 code

D)

2421 code

Correct Answer : 8421 code

Explanation : A sequential code is a code where each succeeding code is one binary number more than the preceding code. Thus, 8421 is a sequential code. Sequential codes are useful in manipulating mathematical data.

A)

2421 and 8421

B)

2421 and 5211

C)

5421 and 2421

D)

5211 and 8421

Correct Answer : 2421 and 5211

Explanation : A reflexive code is the one where the code for 9 is the complement of code for 0, code for 8 is the complement of code for 1, and so on. Thus, 2421 and 5211 are reflexive codes.

A)

It is a reflexive code but not a sequential code

B)

It is a reflexive as well as a sequential code

C)

It is a sequential code but not a reflexive code

D)

It is neither a reflexive code nor a sequential code

Correct Answer : It is a reflexive as well as a sequential code

Explanation : A reflexive code is a code where the code for 9 is the complement of code for 0 and so on. A sequential code is a code where each succeeding code is one binary number more than the preceding code. Excess – 3 code satisfies both these properties.

A)

Adders

B)

Attenuator

C)

Subtractors

D)

Demultiplexer

Correct Answer : Adders

Explanation : The basic building blocks of the arithmetic unit in digital computers are known as adders. Adder is the Arithmetic mathematical function derived out of Logic gates. So, Adder always plays a major role in understanding Digital Electronics. The simplest but the most powerful application of logic gates is Adder. A full adder is similar to a half adder except that instead of 2 inputs and two outputs, there are now three inputs and two outputs. The inputs are carry-in (Cin), X, and Y. Your outputs remain the same, sum, and carry-out (Cout).

A half adder is typically only useful for "single digit" addition. A full adder implements the half Adder to link multiple full adders together to achieve higher orders of addition. Sixteen full adders in the group allow 16- bit addition.

A)

32

B)

16

C)

8

D)

2

Correct Answer : 2

Explanation : The total number of inputs in a half adder is 2. The half adder circuit has two inputs: P and Q, which add two input digits and generate a carry and sum. With the help of half Adder, we can design circuits capable of performing simple addition with the help of logic gates. An EXOR gate has two inputs and carries links to input EXOR gates. The output of the half added is also two, SUM and CARRY.

A)

It is used to divide address bus and data bus.

B)

To convert non coded information into a binary coded form.

C)

To convert coded information into a non-coded form.

D)

None of the above

Correct Answer : To convert coded information into a non-coded form.

Explanation : Decoder is usually used to convert the coded information (BCD) into a non-coded form. In other words, decoders are defined as an electronic device that is used to convert digital signal to an analog signal. The decoders are used in many communication devices that are used to communicate between two devices. The decoder allows n number of inputs and generates 2n numbers of outputs. For example, if we give two inputs, four by two decoder will produce four outputs.

A)

Duality law

B)

Consensus law

C)

Distributive law

D)

Absorption law

Correct Answer : Absorption law

Explanation : The results “X + XY = X” and “X(X + Y) = X” follows the absorption law. The expression given can be written in the form X + XY = X(1 + Y). Any value – added with 1 will give 1 itself. Therefore 1 + Y = 1 and X + XY = X.

A)

It is a buffer

B)

It is a one â€“ bit comparator

C)

It is a one â€“ bit inverter

D)

It is a universal gate

Correct Answer : It is a one â€“ bit comparator

Explanation : Ex – NOR gate is a one – bit comparator as the output for the gate is 1 if similar inputs are given to the gate and output is 0 if different inputs are given to the gate.

A)

OR and AND

B)

XOR and XNOR

C)

AND and OR

D)

XNOR and XOR

Correct Answer : XOR and XNOR

Explanation : XNOR gate is called coincidence gate and gives 1 if similar inputs are given to the gate and output is 0 if different inputs are given to the gate. XOR gate is called anti – coincidence gate and gives 0 if similar inputs are given to the gate and output is 1 if different inputs are given to the gate.

A)

One input many outputs

B)

One input one output

C)

Many outputs to one input

D)

None of the above

Correct Answer : One input many outputs

Explanation : A demultiplexer or DEMUX is a device that takes a single input line and routes it to one of several digital output lines. A demultiplexer of 2n outputs has n number of select lines, which are used to choose which output line send the input. A demultiplexer is also known as data distributor.

A)

The group of flip-flops for storing n bit of information

B)

The group of transistors for storing n- a bit of information

C)

The group of flip-flops for storing binary information

D)

The group of transistors for storing two bits of information

Correct Answer : The group of flip-flops for storing binary information

Explanation : An electronic register refers to a form of memory that uses a group of flip-flops that is suitable for storing binary information, such as a byte (8 bits) of data. Each flip flop is a binary cell suitable for storing individual bits of a binary word. The length of the stored binary information depends on the number of flip-flops that make up the register. The information in a register can be transferred form one flip-flop to another flip-flop.

A)

A register has no specific sequence of states.

B)

A register counts data.

C)

A counter has no particular sequence of states.

D)

A counter has the capability to store n bit of information whereas a register has one bit.

Correct Answer : A register has no specific sequence of states.

Explanation : The primary difference between a counter and a register is that register has no specific state sequence except in certain conditions.

A counter is a special case of a register while the register has the same clock. generally, the register can only be stored, loaded, or used for the stack or as the program counter. The counter does not need to have the same clock.**Advantages of Counter :** It is used in frequency dividers, Code generators and Period and sequence generators.**Advantages of Register :** To Produce Time delay, Simplify Combinational Logic and Convert Serial Data to Parallel Data

A)

2

B)

4

C)

8

D)

16

Correct Answer : 16

Explanation : In Digital Circuits, a frequency division of 2n of the pulsed clock signal can be obtained by connecting n flip – flops in cascade. Thus, for 4 flip – flops clock frequency can be divided by 16.

A)

B)

YZ

C)

X + X

D)

2YZ

Correct Answer : YZ

Explaination :

Using Boolean identities of Digital Electronics the expression XYZ + XYZ can be reduced. According to Complementarity identity X + X = 1. Thus, YZ + XYZ = (X + X)YZ = YZ.

A)

It has one 3 â€“ input AND gate

B)

It has four 3 â€“ input AND gates

C)

It has one 3 â€“ input AND gate

D)

It has four 2 â€“ input AND gates

Correct Answer : It has four 3 â€“ input AND gates

Explanation : A 4 x 1 multiplexer has 2 select lines, 4 input lines, and 1 output line. AND gates are required to pass the inputs. Thus 4 AND gates will be used for each input. 3 – input AND gate is used, where 2 inputs come from each of the select lines and 1 input for the data.

A)

Logic pin

B)

Preset pin

C)

Enable pin

D)

Selection pin

Correct Answer : Enable pin

Explanation : An enable pin allows to activate and deactivate the multiplexer. When enable pin is 0, the output is obtained while when enable pin is 0, the multiplexer is disabled.

A)

Input signals expected in future

B)

Input signals from the past condition

C)

Input signals at the present moment

D)

Input signals from both past and present

Correct Answer : Input signals at the present moment

Explanation : The output in a combinational circuit depends on the mixture of input signals present at that moment. It is not determined by the past conditions. The output in a synchronous circuit depends on the mixture of input signals present at that moment and also the past conditions.

A)

3 mV

B)

30 mV

C)

300 mV

D)

None of the above

Correct Answer : 30 mV

Explaination :

A)

1, 2

B)

2, 3

C)

1, 3

D)

1, 2, 3

Correct Answer : 2, 3

A)

input combination at that time

B)

present output and previous output

C)

input combination and previous input

D)

input combination and previous output

Correct Answer : input combination at that time

A)

C 403

B)

E 304

C)

D 403

D)

D 402

Correct Answer : D 402

Explaination :

A)

Bisecting the SCRs diagonally

B)

Bisecting the SCRs top two layers

C)

Bisecting the SCRs bottom two Layers

D)

Bisecting the SCRs top two and bottom two layers

Correct Answer : Bisecting the SCRs top two and bottom two layers

Explanation : The two- transistor model of the SCR is obtained by bisecting the SCRs top two and bottom two layers. The two-transistor analogy of SCR refers to a method of producing an SCR as a combination of an np-n and a p-np transistor. SCR is a three-terminal device having a p-n-p-n structure. The three terminals of the junctions are the cathode, anode and gate terminal.

A)

To suppress odd harmonics.

B)

Remove ripples from the rectified output.

C)

Maximize AC input variations

D)

Minimize DC input and AC output variations.

Correct Answer : Remove ripples from the rectified output.

Explanation : The main function of the filter in a rectifier circuit is to remove ripples from the rectified output. As we know, rectifiers are primarily used to convert alternating current (AC) to direct current (DC). There we find a considerable AC component in the output, which is called ripple.

Many electronic systems require pure direct current supply to drive or power them. To make a efficient continuous power supply that gives pure DC output, we need to remove the AC component from the output of rectifiers.

A)

All flip-flops are present with data.

B)

All flip-flops are set with data.

C)

It means a parallel shifting of data.

D)

Each flip flop is loaded with data simultaneously.

Correct Answer : All flip-flops are present with data.

Explanation : The actual meaning of the parallel load of a shift register is all flip-flops are present with data. It means that all of the register stages are loaded at a time with new data bits by a single load pulse. In the present condition, the outputs of flip flops will be 1. The value of Preset equals 1 means Q equals 1, this the value of the input is definitely 1.

A)

10

B)

100

C)

1000

D)

10000

Correct Answer : 10

Explanation : Decade counter is divide by 10 counter.

A)

1100

B)

1001

C)

1010

D)

1000

Correct Answer : 1010

Explanation : 1010 = 8 + 0 + 2 + 0 = 10.

A)

10 V

B)

9.45 V

C)

9 V

D)

8 V

Correct Answer : 9.45 V

Explanation :

A)

8

B)

9

C)

10

D)

12

Correct Answer : 9

Explaination :

3 x 512 + 7 x 64 + 5 x 8 + 3

= (2 + 1) x 2^{9} + (4 + 2 + 1)2^{6} + (4 + 1)2^{3} + (2 + 1)

= 2^{10} + 2^{9} + 2^{8} + 2^{7} + 2^{6} + 2^{5} + 2^{3} + 2^{1} + 1

= 2^{10} + 2^{9} + 2^{8} + 2^{7} + 2^{6} + 2^{5} + 2^{3} + 2^{1} + 2^{0}

9 term of power two

Hence number of '1' is 9.

A)

1 M x 16

B)

2 M x 16

C)

3 M x 8

D)

5 M x 8

Correct Answer : 5 M x 8

Explaination : Bits are 40 M, 16 M and 32 M.

A)

100 ns

B)

75 ns

C)

50 ns

D)

25 ns

Correct Answer : 100 ns

Explanation : In ripple counter all the delays are added.

A)

3

B)

4

C)

5

D)

10

Correct Answer : 4

Explanation : 2^{3} = 8 and 2^{4} = 16 Therefore 4 flip-flops are needed. Some states will be skipped to give a modulus of 10.

A)

carry flag will be set but zero flag will be reset

B)

carry flag will be reset but zero flag will be set

C)

both carry flag and zero flag will be reset

D)

both carry flag and zero flag will be set

Correct Answer : carry flag will be set but zero flag will be reset

A)

active signal

B)

toggle signal

C)

debug signal

D)

clock signal

Correct Answer : clock signal

A)

no minority carriers and very high voltage drop in forward direction

B)

large number of minority carriers and very low voltage drop in forward direction

C)

no minority carriers and very low voltage drop in forward direction

D)

large number of minority carriers and very high voltage drop in forward direction

Correct Answer : no minority carriers and very low voltage drop in forward direction

211 .

A)

associative law

B)

distributive law

C)

commutative law

D)

commutative, associative and distributive law

Correct Answer : commutative, associative and distributive law

A)

gain band width product

B)

(propagation delay time) (power dissipation)

C)

(fan out) (power dissipation)

D)

(noise margin) (power dissipation)

Correct Answer : (propagation delay time) (power dissipation)

A)

executes the program

B)

assembles the program

C)

change the program into binary form

D)

change high level Programming language into low level machine language

Correct Answer : change high level Programming language into low level machine language

A)

240

B)

232

C)

228

D)

210

Correct Answer : 240

Explanation :

As we know, the total number of states in the Jhonson counter is determined by the given formula

2^{N} = 2 ^{8}= 256

Now,

the total number of used states = 2N = 2* 8 = 16

therefore, the total number of unused states = 256-16 = 240

A)

1

B)

5

C)

7

D)

9

Correct Answer : 1

Explaination :

In common emitter, the term **β** stands for **current gain**. Current gain refers to the ratio between collector current and base current at a constant V_{CE}.

**β = I _{C}/I_{B}**

In the common base, DC gain α refers to the ratio of the collector current I_{C} and the emitter current I_{E}.

The equation of dc current gain

**α = I _{C}/I_{E}**

Now, we can establish the relationship between α and β

**β = α/ (1 - α)**

Given

**Emitter current I _{E }= 55 mA**

**Collector current I _{C} = 110 mA**

**α = I _{C}/I_{E }= 110/55 = 2**

β = α/ (1 - α) = 2/ (1 - 2)

β = -2

Here the negative value of β indicates its direction, because by convention positive current is always termed as flowing into the device. So, the current gain is negative.