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RRB JE EC CBT Test 2 - Railways MCQ


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150 Questions MCQ Test RRB JE (Railways Junior Engineer) CBT Mock Test Series 2024 - RRB JE EC CBT Test 2

RRB JE EC CBT Test 2 for Railways 2024 is part of RRB JE (Railways Junior Engineer) CBT Mock Test Series 2024 preparation. The RRB JE EC CBT Test 2 questions and answers have been prepared according to the Railways exam syllabus.The RRB JE EC CBT Test 2 MCQs are made for Railways 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for RRB JE EC CBT Test 2 below.
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RRB JE EC CBT Test 2 - Question 1

Which of the following topology describes multipoint connections?

Detailed Solution for RRB JE EC CBT Test 2 - Question 1

A multipoint (also called multidrop) connection is one in which more than two specific devices share a single link.

In a multipoint environment, the capacity of the channel is shared, either spatially or temporally. If several devices can use the link simultaneously, it is a spatially shared connection. If users must take turns, it is a timeshared connection.

A bus topology describes multipoint connections. In bus topology one long cable act as a backbone to link all the devices in a network.

RRB JE EC CBT Test 2 - Question 2

A set of programs which enables computer hardware and software to work together is called

Detailed Solution for RRB JE EC CBT Test 2 - Question 2

System software is a type of computer program that is designed to run a computer's hardware and application programs. If we think of the computer system as a layered model, the system software is the interface between the hardware and user applications.

RRB JE EC CBT Test 2 - Question 3

Which of the following is used to retrieve the information through URL (e.g. http://XYZ.com) on the world wide web?

Detailed Solution for RRB JE EC CBT Test 2 - Question 3
  • web browser is a software application for accessing information on the World Wide Web
  • URL is an acronym for Uniform Resource Locator, It is a reference to the resource on the internet
  • client is a computer that connects to and uses the resources of a remote computer, or server
  • The server handles the request from the web browser and sends back a response to build a connection to provide web services
  • Cookies are messages that web servers pass to the web browser when user visit Internet sites
RRB JE EC CBT Test 2 - Question 4

The frequency with which an earth station communicates with the satellite is called?

Detailed Solution for RRB JE EC CBT Test 2 - Question 4
  • The transmission of a signal from the first earth station to satellite through a channel is called uplink
  • The transmission of a signal from the satellite to second earth station through a channel is called downlink
  • Uplink frequency is the frequency at which, the first earth station is communicating with the satellite
  • The satellite transponder converts this signal into another frequency and sends it down to the second earth station
  • This frequency is called Downlink frequency; In a similar way, the second earth station can also communicate with the first one
RRB JE EC CBT Test 2 - Question 5

Which of the following folk/tribal dances is associated with Karnataka?

Detailed Solution for RRB JE EC CBT Test 2 - Question 5

Yakshagana is a popular folk-theatre form of Karnataka with a long history of nearly four hundred years. It is a unique harmony of musical tradition, eye-catching costumes, and authentic styles of dance, improvised gestures and acting with its extemporaneous dialogue appealing to a wide range of the community. It is a vibrant and vigorous living form of theatre art.

RRB JE EC CBT Test 2 - Question 6

The number of memory location in a microprocessor is determined by

Detailed Solution for RRB JE EC CBT Test 2 - Question 6

Address Bus:

  • On address bus lines the CPU sends out the address of the memory location that is to be written to or read from
  • The number of address lines determines the number of the memory location that the CPU can address
  • Address bus is unidirectional

Data Bus:

  • The data bus is bidirectional
  • This means CPU can read data in from memory or from a port on these lines or it can send data out to memory or to a port from these lines

System bus

  • The system bus is the communication path between bus and peripherals
RRB JE EC CBT Test 2 - Question 7

A 220 Ω resistor is connected in series with the gate of an SCR as shown in fig. The gate current required to fire the SCR is 7 mA. What is the input voltage (Vin) required to fire the SCR?

Detailed Solution for RRB JE EC CBT Test 2 - Question 7

The input voltage must overcome the junction voltage between the gate and cathode (0.7V) and cause 7 mA to flow through the 220 Ω resistor. According to Kirchhoff’s voltage law, Vin us given by:
Vin = VGK + IGR
= 0.7V + (7 mA) (220 Ω) = 2.24 V

RRB JE EC CBT Test 2 - Question 8

The main difference in Colpitts oscillator over Hartley oscillators is

Detailed Solution for RRB JE EC CBT Test 2 - Question 8

A Colpitts oscillator uses two capacitors in place of the two inductors of a Hartley oscillator.
Colpitts oscillator

Hartley oscillator

RRB JE EC CBT Test 2 - Question 9

The size of the pixel depends on the _______.

Detailed Solution for RRB JE EC CBT Test 2 - Question 9

Images are also represented by bit patterns. In its simplest form, an image is composed of a matrix of pixels (picture elements), where each pixel is a small dot. The size of the pixel depends on the resolution. For example, an image can be divided into 1000 pixels or 10,000 pixels.

RRB JE EC CBT Test 2 - Question 10

The Gross Domestic Product of a country is defined as which among the following?

Detailed Solution for RRB JE EC CBT Test 2 - Question 10
  • The Gross Domestic Product is defined as the total value of the finished goods and services produced within the boundary of a country in a financial year. 
  • The GDP of India has shown a growth of 8.2% in the first quarter of the FY 2018-19. 
RRB JE EC CBT Test 2 - Question 11

Consider the following statements
i) Astable Multivibrator can be used for generating a square wave
ii) Bistable Multivibrator can be used for storing binary information

Detailed Solution for RRB JE EC CBT Test 2 - Question 11

Astable Multivibrator shifts between two states thereby generating a square wave. In Bistable Multivibrator, a trigger pulse is needed for change from one stable state to another stable state (from 0 to 1 and 1 to 0) hence can be used to state binary data.

RRB JE EC CBT Test 2 - Question 12

Simplify the Boolean expression f = PQRS + PQR + PQ

Detailed Solution for RRB JE EC CBT Test 2 - Question 12

f = PQ (RS + R + 1)
f = PQ (1)
f = PQ

RRB JE EC CBT Test 2 - Question 13

The first page of a web site is called its:

Detailed Solution for RRB JE EC CBT Test 2 - Question 13

The home page is the first page that we see when a website is opened on the web browser. It is also called the start page or the main page, though home page is a more commonly used name. It is generally made attractive and contains various hyperlinks to different pages within the web site to attract visitors to its site. Some web sites require users to login to the web site to access the home page.

RRB JE EC CBT Test 2 - Question 14

Phosphor coating for cathode ray tubes is provided on

Detailed Solution for RRB JE EC CBT Test 2 - Question 14

The screen is coated with fluorescent material called phosphor which emits light when bombarded by electrons. Phosphor coating for cathode ray tubes is provided on inside surface only.

RRB JE EC CBT Test 2 - Question 15

In January 2019, Krishna Sobti passed away. She was a famous ________.

Detailed Solution for RRB JE EC CBT Test 2 - Question 15
  • Krishna Sobti was a famous Hindi writer and essayist.
  • She had won the Sahitya Akademi Award in 1980 for her novel Zindaginama.
  • She was awarded the Jnanpith in 2017 for her contribution to Indian literature.
  • Some of her celebrated works include Daar Se Bichhudi, Mitro Marjani, Zindaginama, Dil-o-Danish etc.
RRB JE EC CBT Test 2 - Question 16

Which of the following categories of the network has the smallest geographic area?

Detailed Solution for RRB JE EC CBT Test 2 - Question 16

WAN is a Wide Area Network, WANs are typically used to connect comparatively large geographical area such as; a state, a country, a continent, the Internet WANs can span over a range of huge area of a 100,000-kilometre radius >WANs have its ownership and management is distributed, it cannot be handled at the individual level

A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus etc.

LANs can span over a limited range i.e. of 1 km in radius MAN is Metropolitan Area Network and is used to connect two or more LANs in a common geographic area: say a city or a group of buildings MANs can span in the range of 5 to 50 kilometres in diameter.

A personal area network, or PAN, is a computer network that enables communication between computer devices near a person. The range of a PAN typically is a few meters. Examples of wireless PAN, devices include cell phone headsets, wireless keyboards, wireless mice, printers, bar code scanners and game consoles.

RRB JE EC CBT Test 2 - Question 17

Which is/are abiotic component?
I. Sunlight
II. Plants
III. Water
IV. Animals
V. Soil
VI. Insects

Detailed Solution for RRB JE EC CBT Test 2 - Question 17

The natural environment components can be classified into two

  1. Abiotic components
  2. Biotic components

Abiotic components
These components are not living but can support other living organisms. Some kinds of such organisms are given below:

  • Inorganic substances: The elements which are taken up by the plants with the help of sunlight and converted into food. The examples of such inorganic elements are like nitrogen, calcium, phosphorus, hydrogen, carbon dioxide and oxygen.
  • Organic substances: The substances which are taken in the form of inorganic materials from the food source and are again sent back to the environment after decomposition by decomposers. E.g. Carbohydrates, proteins, fats etc.
  • Physical factors: These factors have a direct effect on living organisms, which are climatic conditions like temperature, rainfall, wind, humidity, soil and light energy which is used by the plants for the preparation of food.
  • Lithosphere: The outermost layer of the earth (i.e.) soil or land.
  • Hydrosphere: Part of the earth having water resources like oceans, rivers, ponds, and lakes.
  • Atmosphere: It is a cover around the earth composed by a variety of gases which protects the living organisms from various harmful cosmic radiations.

Biotic components
The area in which life is possible is called as a biosphere. All living organism in the biosphere depends upon one another and these organisms exist in the biosphere forming the following community.

  • Producers: The green plants present on earth surface which produces their own food only once by the process of photosynthesis in sunlight, water, and carbon dioxide forms food for other organisms. E.g. Sugar, carbohydrates etc.
  • Consumer: This organisms directly (or) indirectly depend upon the green plants for the source of food. E.g. All animals including man.
  • Decomposers: These are micro-organisms which decompose the complex compounds in the dead organic matter of plants and animals and again recycle the elements into the environment. E.g. Bacteria and fungi.

​So for the given conditions:

  • Biotic Components – Plants, Animals, Fungi, Insects
  • Abiotic Components – Sunlight, Water, Soil.
RRB JE EC CBT Test 2 - Question 18

The octal equivalent of 1100101.001010 is ______ .

Detailed Solution for RRB JE EC CBT Test 2 - Question 18

Grouping in groups of three

RRB JE EC CBT Test 2 - Question 19

8257 can interface with __ IO devices

Detailed Solution for RRB JE EC CBT Test 2 - Question 19

Some of the features of 8257 are:

  • It has four channels which can be used over four I/O devices
  • Each channel has 16-bit address and a 14-bit counter
  • Each channel can transfer data up to 64kb
  • Each channel can be programmed independently
  • Each channel can perform read transfer, write transfer and verify transfer operations
  • It generates MARK signal to the peripheral device that 128 bytes have been transferred
  • It requires a single-phase clock
  • Its frequency ranges from 250Hz to 3MHz
  • It operates in 2 modes, i.e., Master mode and Slave mode
RRB JE EC CBT Test 2 - Question 20

The size of the earth wire is determined by

Detailed Solution for RRB JE EC CBT Test 2 - Question 20

The main function of the earth wire is to prevent live wire from overloading and absorbs the excess electrons & flows to the ground. The size of the earth wire is determined by the ampere capacity of the service wires. Minimum size of earth wire for light circuit is 1 mm square for copper and 1.5 mm square for aluminum.

RRB JE EC CBT Test 2 - Question 21

What is the formula of Ethanoic acid?

Detailed Solution for RRB JE EC CBT Test 2 - Question 21
  • Acetic acid, commonly named ethanoic acid, is a colorless liquid organic compound with the chemical formula CH3COOH.
  • When undiluted, it is sometimes called glacial acetic acid.
RRB JE EC CBT Test 2 - Question 22

Avalanche breakdown diodes have breakdown voltage

Detailed Solution for RRB JE EC CBT Test 2 - Question 22
  • Avalanche breakdown occurs in lightly-doped p-n junctions where the depletion region is comparatively long
  • The doping density controls the breakdown voltage
  • The temperature coefficient of the avalanche mechanism is positive; that is, as the temperature increases, so do the reverse breakdown voltage
  • The magnitude of the temperature coefficient also increases with an increased breakdown voltage
  • For example, the temperature coefficient of an 8.2 V diode is in the range 3 - 6 mV/K while the temperature coefficient of an 18 V diode is in the range of 12 - 18 mV/K
RRB JE EC CBT Test 2 - Question 23

Concatenation operator in SQL* plus –

Detailed Solution for RRB JE EC CBT Test 2 - Question 23

Concatenation operator || Concatenate columns or character strings to other columns is SQL.
eg. SELECT ‘Name’ || enamename FROM emp;

Output will be:
Name = JONES
Name = SMITH
So, one can merge the output of 2 or more columns together using concatenation operator ||.

RRB JE EC CBT Test 2 - Question 24

What is the total resistance of a voltmeter on the 10 V range when the meter movement is rated for 50 μA of full-scale current?

Detailed Solution for RRB JE EC CBT Test 2 - Question 24

RRB JE EC CBT Test 2 - Question 25

If the input to full wave rectifier is a sinusoidal signal with frequency 50 Hz, then the time period of the ripple at the output of full wave rectifier is:

Detailed Solution for RRB JE EC CBT Test 2 - Question 25

  • If the input frequency is 50 Hz, the output frequency will be 100 Hz
  • ripple frequency at the output is two times of input frequency
  • timeperiod = 1/f = 1/100 = 10msec
RRB JE EC CBT Test 2 - Question 26

The early effect in a bipolar junction transistor is caused by

Detailed Solution for RRB JE EC CBT Test 2 - Question 26
  • A large collector base reverse bias is the reason behind early effect manifested by BJTs
  • The depletion layer penetrates more into the base as the base is lightly doped increasing the concentration gradient in the base
  • As reverse biasing of the collector to base junction increases, depletion region penetrates more into the base, this reduces the effective base width
  • This reduction in base width causes less recombination of carriers in the base region
  • This is known as an early effect
RRB JE EC CBT Test 2 - Question 27

A Johnson ring counter with N states has _______ flip flops:

Detailed Solution for RRB JE EC CBT Test 2 - Question 27

n-bit Johnson ring counter has 2n states.

Thus, if a Johnson counter has n states then the number of flip flops required are N/2.

RRB JE EC CBT Test 2 - Question 28

Unit of deflection sensitivity of CRO is

Detailed Solution for RRB JE EC CBT Test 2 - Question 28

The "deflection sensitivity" is defined as the ratio of the deflection of the electron beam at the screen of the CRT to the deflection voltage. Unit of deflection sensitivity of CRO is meter/volt

RRB JE EC CBT Test 2 - Question 29

Why is the Caps Lock key referred to as a toggle key?

Detailed Solution for RRB JE EC CBT Test 2 - Question 29

A toggle key toggles the input from other keys on the keyboard between different input modes.

  • The most commonly used toggle key is the caps lock key, which alternates the letter keys between uppercase and lowercase
  • Num lock is another toggle key which helps to input numerals from the numeric keyboard and is turned on by default
  • Scroll lock key allows arrow keys to scroll through window's contents and allows users to scroll without depending on the scroll bar
  • The insert key is another example of a toggle key, and it toggles between overtype mode and insert mode while entering text
RRB JE EC CBT Test 2 - Question 30

Which mirror is used by doctors to examine the eyes, ears, nose, and throat?

Detailed Solution for RRB JE EC CBT Test 2 - Question 30
  • When the object is between the centre of curvature and focus or between focus and pole of a concave mirror, the image formed is virtual, erect and magnified.
  • Therefore, doctors use concave mirrors to examine the eyes, ears, nose,and throat from a close range as the image formed is enlarged and provides a better view to the doctor.
RRB JE EC CBT Test 2 - Question 31

A moving iron type ammeter has few turns of thick wire so that

Detailed Solution for RRB JE EC CBT Test 2 - Question 31

Thick wire implies a large area which along with fewer turns provide a low internal resistance to the ammeter. This low internal resistance is required so that complete branch current can pass through the ammeter.

RRB JE EC CBT Test 2 - Question 32

The function of cleaver is:

Detailed Solution for RRB JE EC CBT Test 2 - Question 32

Various instruments and their functions are:

Fusion Splicing Machine:
It melts the two ends of fibre optic cables together to form a continuous cable.

Optical Time Domain Reflectometer (OTDR)

An OTDR may be used for estimating the fibre’s length and over all attenuation, including splice and mated-connector losses.

Cleaver
A perpendicular cut in an optical fibre cable is critical to the success of the splice or joint. A cleaver breaks the glass cable with high precision.

RRB JE EC CBT Test 2 - Question 33

A duplexer in radar is also called as:

Detailed Solution for RRB JE EC CBT Test 2 - Question 33
  • A duplexer is a device that isolates transmitter while receiving an isolated receiver while transmitting
  • A duplexer is basically an electronic switch
  • It acts like a transmit/ Receive switch and is also called as TR Switch
RRB JE EC CBT Test 2 - Question 34

The optical properties of liquid crystals depend on the direction of

Detailed Solution for RRB JE EC CBT Test 2 - Question 34
  • The optical properties of liquid crystals depend on the direction light travels through a layer of the material
  • An electric field can change the orientation of molecules in a layer of liquid crystal and thus affect its optical properties
RRB JE EC CBT Test 2 - Question 35

When did Constituent Assembly adopt Constitution?

Detailed Solution for RRB JE EC CBT Test 2 - Question 35
  • The Constitution of India was adopted by the Constituent Assembly on 26th November, 1949 but it came into force on 26th January, 1950.
  • Constitution of India is known as the supreme law of India which consists of fundamental political codes, powers, procedures, structures and the duties of the government institutions, directive principles and the duties of the citizen.
  • It is the longest written constitution of any country in the world.
  • B.R. Ambedkar was considered to be its chief architect as he was the Chairman of the Drafting Committee
RRB JE EC CBT Test 2 - Question 36

Which of the following data structure is used for converting the infix notation to postfix notation?

Detailed Solution for RRB JE EC CBT Test 2 - Question 36

The conversion of infix notation to postfix notation is done by using Stack.

Infix Expression is in form <Operand><Operator><Operand>, Eg: A + B

Postfix Expression is in form <Operand><Operand><Operator>, Eg: AB+

RRB JE EC CBT Test 2 - Question 37

What is the maximum possible range of bit count specifically in n-bit binary counter consisting of ‘n’ number of flip flops?

Detailed Solution for RRB JE EC CBT Test 2 - Question 37

The range of bit count specifically in n-bit binary counter consisting of ‘n’ number of flip flops is 0 to 2n - 1

E.g.
For 1 bit
Range: 0 to 2- 1 = 0 to 1

For 2 bits
Range: 0 to 2- 1 = 0 to 3 (00, 01, 10, 11)

For 3 bits
Range: 0 to 2- 1 = 0 to 7 (000, 001, 010, 011, 100,101, 110, 111)
A n-bit counter count n state from 0 to 2- 1

RRB JE EC CBT Test 2 - Question 38

LAN covers

Detailed Solution for RRB JE EC CBT Test 2 - Question 38

LAN connects computers and workstation in office or home. It covers a local area of 1 km. campus area network (CAN) covers privately owned campus with an area of 5 to 10 kms. MAN covers town or city with an area of 2 to 100 kms. Whereas WAN spans a large geographical area of more than 100 kms.

RRB JE EC CBT Test 2 - Question 39

Diffusion capacitance is_______ than/to transition capacitance.

Detailed Solution for RRB JE EC CBT Test 2 - Question 39

Transition capacitance is given by 

Where
W = xn + xp
Diffusion Capacitance is given by 

Since the depletion region width is more in reverse bias the diffusion capacitance is more than transition capacitance

RRB JE EC CBT Test 2 - Question 40

Which one of the following is a collection of variables having different data types under a single name?

Detailed Solution for RRB JE EC CBT Test 2 - Question 40

Structure creates a data type that can be used to group items of possibly different types into a single type.

Example:

struct Point

{

 int x;

 float y;

} p1;

void main()

{

 /*We can also declare object here as

 Point p1; */

            p1.x = 5;

            p1.y = 5.05;

}

RRB JE EC CBT Test 2 - Question 41

A full – adder can be implemented with half – adders and OR gates. A 4 – bit parallel full adder without any initial carry requires

Detailed Solution for RRB JE EC CBT Test 2 - Question 41

A full adder can be implemented with 2 half adders and one OR gate.
A 4-bit parallel adder can be implemented using 3 full adders and one half adder.
Hence we require 7 half adders and 3 OR gates to implement 4-bit parallel adder.

RRB JE EC CBT Test 2 - Question 42

Which of the following is an operating system?
I. Ubuntu
II. Linux
III. Unix

Detailed Solution for RRB JE EC CBT Test 2 - Question 42

Ubuntu, Linux, Unix, Microsoft Windows and macOS all fall under the category of operating systems.

An Operating system is basically a low-level system software and an important program that runs on every computer. Its basic function is to perform basic tasks such as controlling peripherals, managing computer software and hardware resources, keeping track of directories and files in the storage drive, sending output to the display and more.

RRB JE EC CBT Test 2 - Question 43

Which of the following is an analogue transducer?

Detailed Solution for RRB JE EC CBT Test 2 - Question 43

Analog transducers:

  • These transducers convert the input quantity into an analog output which is a continuous function of time
  • Thus, a strain gauge, an L.V.D.T., a thermocouple or a thermistor may be called as Analog Transducers as they give an output which is a continuous function of time

Digital Transducers:

  • These transducers convert the input quantity into an electrical output which is in the form of pulses and its, output is represented by 0 and 1
RRB JE EC CBT Test 2 - Question 44

Which of the following is the main constituent of Biogas after Methane?

Detailed Solution for RRB JE EC CBT Test 2 - Question 44
  • Methane and Carbon dioxide are the main constituent of Biogas.
  • Methane is produced by the anaerobic bacterial decomposition of vegetable matter under water.
  • It is also known as marsh gas or swamp gas.
  • Its chemical formula is CH4.
RRB JE EC CBT Test 2 - Question 45

The time period of oscillations of 555 timer IC is given by:

Detailed Solution for RRB JE EC CBT Test 2 - Question 45

Time period high of 555 timers is given by
THigh = 0.693(R+ RB) C
Tlow = 0.693 RBC
Thus, total time period T is given by
T = THigh + Tlow
T = 0.693 (R+ 2 RB) C

RRB JE EC CBT Test 2 - Question 46

The output stage of an op-amp amplifier is:

Detailed Solution for RRB JE EC CBT Test 2 - Question 46

The various stages of op-amp are shown in the figure:
The last stage/output stage is the Push Pull amplifier

RRB JE EC CBT Test 2 - Question 47

Which of the following decisive battles had established the dominion of the British in India?

Detailed Solution for RRB JE EC CBT Test 2 - Question 47

The Battle of Buxarwas fought on 22-23 October 1764 between the forces under the command of the British East India Company led by Hector Munro and the combined armies of Mir Qasim, Nawab of Bengal till 1763; the Nawab of Awadh; and the Mughal Emperor Shah Alam.

  • The combined armies of Mughals, Awadh and MirQasim were defeated by the British army.
  • Treaty of Allahabad was signed after the battle of Buxar.
RRB JE EC CBT Test 2 - Question 48

Which of the following is not a primary parameter of transmission line?

Detailed Solution for RRB JE EC CBT Test 2 - Question 48

The primary parameters of a transmission line are the

  • resistance (R)
  • inductance (L)
  • capacitance (C)
  • conductance. (G)

Secondary parameters of the transmission line are:

  • Attenuation constant (α)
  • Phase constant (β)
  • propagation constant (γ)
RRB JE EC CBT Test 2 - Question 49

Which force is required to maintain a body in Uniform circular Motion?

Detailed Solution for RRB JE EC CBT Test 2 - Question 49
  • The Centripetal force is required to maintain a body in Uniform Circular Motion.
  • Centripetal Force acts when a body moves around the other body, the force that causes this acceleration and keeps the body moving along a circular path is acting towards the centre
RRB JE EC CBT Test 2 - Question 50

Which of the following noise becomes significant at high frequencies?

Detailed Solution for RRB JE EC CBT Test 2 - Question 50

Various types of internal noise are:

  • Shot Noise:
  1. These Noises are generally arising in the active devices due to the random behaviour of Charge particles or carries
  2. In the case of the electron tube, shot Noise is produced due to the random emission of electron form cathodes
  • Partition Noise:
  1. When a circuit is to divide in between two or more paths then the noise generated is known as Partition noise
  2. The reason for the generation is random fluctuation in the division
  • Low- Frequency Noise:
  1. They are also known as FLICKER NOISE
  2. These types of noise are generally observed at a frequency range below few kHz
  3. Power spectral density of these noise increases with the decrease in frequency
  4. That's why the name is given Low- Frequency Noise
  • High- Frequency Noise:
  1. These noises are also known as TRANSIT- TIME Noise
  2. They are observed in the semiconductor devices when the transit time of a charge carrier while crossing a junction is compared with the time period of that signal
  • Thermal Noise:
  1. Thermal Noise is random and often referred to as White Noise or Johnson Noise
  2. Thermal noise is generally observed in the resistor or the sensitive resistive components of a complex impedance due to the random and rapid movement of molecules or atoms or electrons
RRB JE EC CBT Test 2 - Question 51

Which of the following signal ensures that the address is transferred on the bus?

Detailed Solution for RRB JE EC CBT Test 2 - Question 51

Lower 8 pins of microprocessor pins are multiplexed to act for data or address transfer.

Whether the bus is used to carry data or address is decided by the signal on ALE pin.

When
ALE = 1 address is transferred to bus
ALE = 0 Data transfer to bus 

RRB JE EC CBT Test 2 - Question 52

Which of the following is fastest DMA mode?

Detailed Solution for RRB JE EC CBT Test 2 - Question 52

Direct memory access (DMA) is a method that allows an input/output (I/O) device to send or receive data directly to or from the main memory, bypassing the CPU to speed up memory operations.

The process is managed by a chip known as a DMA controller (DMAC).

Burst Mode

  • In burst mode, an entire block of data is transferred in one contiguous sequence
  • Once the DMA controller is granted access to the system bus by the CPU, it transfers all bytes of data in the data block before releasing control of the system buses back to the CPU
  • This renders the CPU inactive for relatively long periods of time

Cycle Steal Mode

  • In DMA's cycle stealing mode of operation, the DMA controller puts the CPU on hold for each byte of data to be transferred.
  • The processor thus knows the fact that the DMA controller is using the bus
RRB JE EC CBT Test 2 - Question 53

Electro-optical effect is produced in

Detailed Solution for RRB JE EC CBT Test 2 - Question 53

The electro-optic effect is the phenomenon that the refractive index of a material can be modified with an electric field and it forms the basis for LCDs.

RRB JE EC CBT Test 2 - Question 54

Three equal resistors of 50 Ω each are connected in parallel across 110 V dc supply. What is the current through each branch if one of the resistors get shorted?

Detailed Solution for RRB JE EC CBT Test 2 - Question 54

When one of the resistor’s is shorted, all the current flows through the short circuit branch.

The current flowing through each resistor then becomes zero.

RRB JE EC CBT Test 2 - Question 55

Which of the following statement is correct about the value of acceleration due to gravity at the poles?

Detailed Solution for RRB JE EC CBT Test 2 - Question 55
  • Due to the equatorial bulge, i.e. the equator being more bulged towards the outside, the poles are nearer to the Centre of the earth, as compared to the equatorial region.
  • And as the acceleration due to gravity is inversely proportional to the distance from the Centre of the earth, as the distance is less on poles, the acceleration due to gravity(g) is more at the poles.
RRB JE EC CBT Test 2 - Question 56

Who among the following has won Australian Open Men’s Singles 2019 title at Melbourn?

Detailed Solution for RRB JE EC CBT Test 2 - Question 56
  • Novak Djokovic defeated Rafael Nadal to win his 7th Australian Open Men’s Singles title at Melbourn.
  • The resurgent world No. 1 outplayed the second-ranked Nadal 6-3, 6-2, 6-3 in a largely one-sided match.
  • In Women’s Singles, Japan’s Naomi Osaka clinched her maiden Australian Open Grand Slam Singles title in Melbourne.
RRB JE EC CBT Test 2 - Question 57

Which quantum number is associated with the angular momentum of the electron?

Detailed Solution for RRB JE EC CBT Test 2 - Question 57
  • The quantum mechanical state of an electron is identified by the following quantum numbers:
  1. Denoted by n, the principal quantum number is always an integer and describes the electron's state.
  2. The Orbital quantum number / azimuthal quantum number is denoted by l and is associated with the angular momentum (L) of the electron due to its orbital motion. It is given by l = n - 1
  3.  The energy of an electron in a hydrogen atom is affected by a strong magnetic field and the quantum number which describes this magnetic effect is called magnetic quantum number. It is denoted by ml.
  4. Denoted by ms, the spin quantum number is associated with the intrinsic angular momentum of the electron.
RRB JE EC CBT Test 2 - Question 58

In the SPWM, the modulating signal is

Detailed Solution for RRB JE EC CBT Test 2 - Question 58
  • In the SPWM, the modulating signal is sinusoidal
  • SPWM output is generated by intersection between sine signal and triangle signal
  • Sine signal is the reference waveform and triangle waveform is the carrier waveform
  • When value sine signal is large than triangle signal, the pulse will start produce to high
RRB JE EC CBT Test 2 - Question 59

To obtain 30 % feedback factor, the correct relation between R1 and R2 is:

Detailed Solution for RRB JE EC CBT Test 2 - Question 59

The feedback factor is given by β

100 R2 = 30 R1 + 30 R2
70 R2 = 30 R1
7 R2 = 3 R1

RRB JE EC CBT Test 2 - Question 60

A computer virus is a

Detailed Solution for RRB JE EC CBT Test 2 - Question 60

A computer Virus is a malicious software that, when executed replicates itself by modifying other computer programs.

The full of VIRUS is Vital Information Recourse Under Siege, because they replicate and multiply and use up computer memory processing power with fake repetitive commands. It causes the system to become slow and keeps hanging.

RRB JE EC CBT Test 2 - Question 61

Which layer of the atmosphere has the maximum concentration of Ozone gas?

Detailed Solution for RRB JE EC CBT Test 2 - Question 61
  • Stratosphere layer of atmosphere has the maximum concentration of Ozone gas.
  • Approximately 10 per cent of Ozone layer is present in Troposphere and rest of the 90 per cent found in Stratosphere layer of atmosphere..
  • Ozone layer in Stratosphere atmosphere absorbs most of the ultraviolet radiation from the Sun.
  • Stratosphere is the second layer of atmosphere whereas Troposphere is the lowest layer of the atmosphere.
  • The Thermosphere is the layer of the Earth's atmosphere is above the Mesosphere.
  • There are five layers of atmosphere namely- Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere. 
RRB JE EC CBT Test 2 - Question 62

What is the full form of 'LAN'?

Detailed Solution for RRB JE EC CBT Test 2 - Question 62

A local area network (LAN) is a computer network within a small geographical area. A LAN is composed of inter-connected workstations and personal computers which are each capable of accessing and sharing data and devices, such as printers, scanners and data storage devices, anywhere on the LAN.

RRB JE EC CBT Test 2 - Question 63

Which of the following living beings is most likely to produce greenhouse gases?

Detailed Solution for RRB JE EC CBT Test 2 - Question 63

Green plants are most likely to produce greenhouse gases.

  • Greenhouse gases consists gases such as carbon dioxide, methane, water vapour, nitrous oxide and ozone.
  • These gases absorbs heat which produced from the Sun.
  • A greenhouse is called so because it is a house which contains green things such as plants and beneficial gasses.
RRB JE EC CBT Test 2 - Question 64

The simplified Boolean expression of Y = A’B’C + A’BC’ + AB’C’ + ABC is:

Detailed Solution for RRB JE EC CBT Test 2 - Question 64

The given expression is Y = Σm (1, 2, 4, 7)
This is the expression for the Sum of a full adder

The sum expression is:
S =  A ⊕ B ⊕ C

Note:
Three input EXNOR and EXOR are not always equivalent.
That concept is only applicable when three input ex nor is constructed using 2 input EX OR gate.
EXNOR gate doesnot follow distribute property

i.e
A ⊙ (B ⊙ C) and (A ⊙ B) ⊙ C are not equivalent 

RRB JE EC CBT Test 2 - Question 65

The leakage current in the transmission line is mapped using the parameter:

Detailed Solution for RRB JE EC CBT Test 2 - Question 65

Capacitance (C)

  • In a two-wire transmission line, conductors are separated by insulating dielectrics(air) in order to store electric charges, gives rise to the capacitance effect
  • The capacitance is distributed in the whole conductor length

Resistance (R)

  • The resistance is a primary parameter that is uniformly distributed along the length of the conductor
  • It depends on the cross-section area and the length of the conductor

Inductance (L)

  • When the conductors in transmission lines carry current, the conductor will be surrounded and linked by magnetic flux
  • The flux linkages per ampere of current give rise to the effect of inductance
  • It is denoted by L

Conductance (G)

  • The dielectrics or insulators of the open wire line may not be perfect, and a leakage current will flow
  • This leakage conductance exists between the conductors
RRB JE EC CBT Test 2 - Question 66

Which logic gate is implemented using by the MUX

Detailed Solution for RRB JE EC CBT Test 2 - Question 66

When B = 0 then the output is A
When B = 1 then the output is A’
Thus, the output is
Y = A’B + AB’
Y = A ⊕ B

RRB JE EC CBT Test 2 - Question 67

Which one of the following is NOT a type of error of ADC?

Detailed Solution for RRB JE EC CBT Test 2 - Question 67

Offset error:
It is defined as a constant difference, over the whole range of the ADC, between the actual output value and the ideal output value.

Gain error:
It is defined as the difference of the slope of the actual output values and the ideal output values.

Non-linearity error
For an ideal ADC, the output is divided into 2n uniform steps each with the width ∆. Any deviation from the ideal step width is the Differential Non-Linearity. (DNL)

RRB JE EC CBT Test 2 - Question 68

VSWR of a perfectly matched transmission line is:

Detailed Solution for RRB JE EC CBT Test 2 - Question 68

The reflection coefficient is given by:

When ZL = Z0 the transmission line is said to be perfectly matched
Γ = 0

Substitute Γ = 0
VSWR = 1

RRB JE EC CBT Test 2 - Question 69

Fly ash is the environmental pollutant generated by

Detailed Solution for RRB JE EC CBT Test 2 - Question 69

Fly ash, also known as "pulverised fuel ash" is a coal combustion product composed of fine particles that are driven out of the boiler with the flue gases in thermal power plant.

RRB JE EC CBT Test 2 - Question 70

Who among the following authored the book 'The Golden Threshold'?

Detailed Solution for RRB JE EC CBT Test 2 - Question 70
  • Sarojani Naidu became the first Indian women president of the Congress at the Kanpur session in 1925.
  • She was the first woman to become the governor of Uttar Pradesh.
  • She began writing at the age of 13. Known as the Nightingale of India, she eulogised India in her poems published in three collections, The Golden Threshold (1905), The Bird of Time (1912) and the Broken Wing (1917).
RRB JE EC CBT Test 2 - Question 71

In the given circuit, determine the current through the 4 Ω resistor

Detailed Solution for RRB JE EC CBT Test 2 - Question 71

The voltage across the 4 Ω resistor is 3V
The current flowing through the resistor is given by

Note: Current source is redundant in parallel with the voltage source

RRB JE EC CBT Test 2 - Question 72

In normal operation of an SCR, gate is ________ w.r.t. cathode

Detailed Solution for RRB JE EC CBT Test 2 - Question 72

When anode is positive w.r.t. cathode, the curve between V and I is called the forward characteristic.

If the supply voltage is increased from zero, a point is reached (point A) when the SCR starts conducting. Under this condition, the voltage across SCR suddenly drops as shown by dotted curve AB and most of supply voltage appears across the load resistance RL. If proper gate current is made to flow, SCR can close at much smaller supply voltage.

RRB JE EC CBT Test 2 - Question 73

Total number of modes 8253 can work in is:

Detailed Solution for RRB JE EC CBT Test 2 - Question 73

8253 can work in 6 modes which are:

  • Mode 0 (000): Interrupt on terminal count
  • Mode 1 (001): programmable one-shot
  • Mode 2 (X10): rate generator
  • Mode 3 (X11): square wave generator
  • Mode 4 (100): Software Triggered Strobe
  • Mode 5 (101): Hardware Triggered Strobe
RRB JE EC CBT Test 2 - Question 74

"Forests" is listed in the _________ list given in the Seventh Schedule in the Constitution of India.

Detailed Solution for RRB JE EC CBT Test 2 - Question 74

Through the 42nd Amendment Act of 1976 five subjects were transferred from State to Concurrent List. They are:
1. Education
2. Forests
3. Weights & Measures
4. Protection of Wild Animals and Birds
5. Administration of Justice

RRB JE EC CBT Test 2 - Question 75

The gain of the RC low pass filter having time constant ‘τ' and frequency ‘ω' is:

Detailed Solution for RRB JE EC CBT Test 2 - Question 75

The Low pass filter is shown below

The transfer function is given by

Time constant RC = τ

RRB JE EC CBT Test 2 - Question 76

Data communication is

Detailed Solution for RRB JE EC CBT Test 2 - Question 76

Data communications are the exchange of data between two devices via some form of transmission medium such as a wire cable. For data communications to occur the communicating devices must be part of a communication system made up of a combination of hardware (physical equipment) and software (programs).

RRB JE EC CBT Test 2 - Question 77

The S.I. unit magnetic permeance is ________

Detailed Solution for RRB JE EC CBT Test 2 - Question 77

Magnetic permeance is the inverse of reluctance. It is a measure of the quantity of magnetic flux for a number of current-turns.
The SI unit of magnetic permeance is webers per ampere-turn that is H (henry).

RRB JE EC CBT Test 2 - Question 78

Chlorofluorocarbons which damage the ozone layer of the atmosphere are not used in which of the following?

Detailed Solution for RRB JE EC CBT Test 2 - Question 78
  • Chlorofluorocarbons (CFC) are used in Refrigerator, Air conditioner and Aerosol spray.
  • Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine.
RRB JE EC CBT Test 2 - Question 79

The full form of LCD is

Detailed Solution for RRB JE EC CBT Test 2 - Question 79

The full form of LCD is Liquid Crystal Display.

  • A liquid crystal display (LCD) is a thin, flat panel used for electronically displaying information such as text, images, and moving pictures
  • It is an electronically-modulated optical device made up of any number of pixels filled with liquid crystals and arrayed in front of a light source (backlight) or reflector to produce images in color or monochrome
RRB JE EC CBT Test 2 - Question 80

Impurities added in metals:

Detailed Solution for RRB JE EC CBT Test 2 - Question 80
  • Metals have a large number of charge carriers, which are free electrons
  • As the impurities/dopants are added there is no significant change in the concentration of carriers
  • The added impurities tend to scatter electrons in the metals
  • This decreases the mobility and hence the conductivity
RRB JE EC CBT Test 2 - Question 81

Very large values of modulation index (greater than 3.24) lead to

Detailed Solution for RRB JE EC CBT Test 2 - Question 81

Modulation index is used to determine the strength and quality of transmitted signal. If the modulation index is small, then the amount of variation in the carrier amplitude is small. Very large values of modulation index (greater than 3.24) lead to a square AC output voltage.

RRB JE EC CBT Test 2 - Question 82

For a single mode optical fibre and a multi-mode optical fibre of the same material, the correct statement is:

Detailed Solution for RRB JE EC CBT Test 2 - Question 82

The numerical aperture of an optical fibre is given by

Where
n= refractive index of the core
n2 = refractive index of cladding

RRB JE EC CBT Test 2 - Question 83

Which of the following chemical compounds is used for causing acid rain? 

Detailed Solution for RRB JE EC CBT Test 2 - Question 83
  • Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air.
  • These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.
  • Sulfur dioxide and nitrogen oxides dissolve very easily in water and can be carried very far by the wind.
  • As a result, the two compounds can travel long distances where they become part of the rain, sleet, snow, and fog that we experience on certain days.
RRB JE EC CBT Test 2 - Question 84

Excess nitrate in drinking water can cause

Detailed Solution for RRB JE EC CBT Test 2 - Question 84


An illness that begins when large amounts of nitrates in water are ingested by an infant and converted to nitrite by the digestive system. The nitrite then reacts with oxy-haemoglobin (the oxygen-carrying blood protein) to form metheglobin, which cannot carry oxygen. If a large enough amount of metheglobin is formed in the blood, body tissues may be deprived of oxygen, causing the infant to develop a blue coloration of their mucous membranes and possibly digestive and respiratory proble