RRB JE EC CBT Test 1

# RRB JE EC CBT Test 1

Test Description

## 150 Questions MCQ Test RRB JE (Railways Junior Engineer) CBT Mock Test Series | RRB JE EC CBT Test 1

RRB JE EC CBT Test 1 for Railways 2023 is part of RRB JE (Railways Junior Engineer) CBT Mock Test Series preparation. The RRB JE EC CBT Test 1 questions and answers have been prepared according to the Railways exam syllabus.The RRB JE EC CBT Test 1 MCQs are made for Railways 2023 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for RRB JE EC CBT Test 1 below.
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RRB JE EC CBT Test 1 - Question 1

### If the refractive index of glass is 1.732, find the Brewster’s angle–

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

We know, μ = tan ip
Where ip = Polarization or Brewster’s angle
∴ ip = tan-1 μ = tan-1(1.732) = 60°

RRB JE EC CBT Test 1 - Question 2

### Which of the following statements are false related to a typical Op-Amp? 1) High Bandwidth 2) High output impedance 3) High CMMR 4) Low slew rate 5) High input impedance

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

An Op-Amp should have
i) High Bandwidth
ii) High input impedance
iii) Low output impedance
iv) High Gain
v) High CMRR
vi) High slew rate

RRB JE EC CBT Test 1 - Question 3

### Residual resistivity of a conductor is measured at

Detailed Solution for RRB JE EC CBT Test 1 - Question 3
• Residual resistivity is the resistivity of material at 0 kelvin
• It depends on the imperfections in the lattice
• It is independent of temperature
RRB JE EC CBT Test 1 - Question 4

Which element is most electronegative among Arsenic, Nitrogen and Phosphorus?

Detailed Solution for RRB JE EC CBT Test 1 - Question 4
• Nitrogen is the most electronegative among Arsenic, Nitrogen and Phosphorus.
• As per the periodic table, Nitrogen has an atomic number of 7 and hence its electron configuration is 1s2 2s2 2p3.
• Amongst all the others nitrogen has the highest tendency to attract a shared pair of electrons towards itself.
RRB JE EC CBT Test 1 - Question 5

In the following figure, When S = R = 1, then the output P and Q are:

Detailed Solution for RRB JE EC CBT Test 1 - Question 5

Truth Table of NAND gate is shown

If one of the inputs is ‘1’ then the output is an inversion of other input.
The NAND based latch truth table is shown

The output will retain its previous state.

RRB JE EC CBT Test 1 - Question 6

The figure shows schematic of a phase locked loop, If the reference voltage has the phase θ and VCO has phase ϕ then the error voltage has phase:

Detailed Solution for RRB JE EC CBT Test 1 - Question 6

The output error voltage of the phase detector is proportional to the phase difference between the reference frequency and VCO signal

Proof:
Let the reference signal be = Accos(ωt+θ)
And VCO signal be = AVsin(ωt+ϕ)A
The phase detector is a multiplier circuit followed by LPF
Thus, the output of the multiplier is

RRB JE EC CBT Test 1 - Question 7

A bipolar transistor has a maximum junction temperature rating of 200°C. If its junction-to-case thermal resistance of 1°C per watt, the transistor can dissipate at the most a power of 100 watts if the case temperature is not to exceed

Detailed Solution for RRB JE EC CBT Test 1 - Question 7

Let the case and junction temperature be T1 and T2. The thermal resistance θ= 1C/W. Then power dissipated PD is given by,

Thus, the case temperature should be, T1 = 100C

RRB JE EC CBT Test 1 - Question 8

The frequency range of moving-iron instruments is

Detailed Solution for RRB JE EC CBT Test 1 - Question 8

RRB JE EC CBT Test 1 - Question 9

Which of the following is a DMA controller?

Detailed Solution for RRB JE EC CBT Test 1 - Question 9

8257 : DMA Controller
8255 : PPI (Programmable Peripheral Interface)
8251 : USART (Universal Synchronous and Asynchronous Receiver Transmitter)
8259 : PIC(Programmable Interrupt Controller)
8253, 8254 : Programmable Timers

RRB JE EC CBT Test 1 - Question 10

Which instrument has the highest frequency range with accuracy within reasonable limits?

Detailed Solution for RRB JE EC CBT Test 1 - Question 10

Rectifier instrument has the highest frequency range with accuracy within reasonable limits. These instruments are nothing but permanent magnet moving coil instruments used in conjunction with rectifying device for AC measurements (current and voltage) from about 20 Hz to 20 kHz.

RRB JE EC CBT Test 1 - Question 11

The gates required to build a half adder are

Detailed Solution for RRB JE EC CBT Test 1 - Question 11

The gates required to build a half adder are EX-OR gate and AND gate.

RRB JE EC CBT Test 1 - Question 12

What is the purpose of the scanf command?

Detailed Solution for RRB JE EC CBT Test 1 - Question 12

The programming language, scanf is the short form of scan formatted. It is a keyword used as a control parameter meant for reading a string. The string is picked up from the standard input device itself.

RRB JE EC CBT Test 1 - Question 13

Which of the following prizes is given for fiction?

Detailed Solution for RRB JE EC CBT Test 1 - Question 13

The Man Booker Prize for Fiction is a literary prize awarded each year for the best original novel written in the English language and published in the UK.

RRB JE EC CBT Test 1 - Question 14

The ratio of maximum efficiency of a half wave rectifier to full wave rectifier is

Detailed Solution for RRB JE EC CBT Test 1 - Question 14

For Half wave rectifier, Efficiency
For Full wave rectifier, Efficiency

RRB JE EC CBT Test 1 - Question 15

The strength of an electromagnet can be increased by introducing a soft iron core

Detailed Solution for RRB JE EC CBT Test 1 - Question 15

The strength of an electromagnet can be increased by introducing a soft iron core inside the coil. We can make the electromagnet stronger by adding more turns to the coil.

RRB JE EC CBT Test 1 - Question 16

The phase difference between the input and feedback in case of oscillators is:

Detailed Solution for RRB JE EC CBT Test 1 - Question 16

For sustained oscillations in an oscillator, there are two conditions that are required to be met:

1. Loop gain Aβ = 1
2. Positive feedback

In the case of positive feedback, the phase difference between input and feedback is 0° or 360°.

RRB JE EC CBT Test 1 - Question 17

For an EM wave travelling in a plane, the correct equation for characteristic impedance Z for the medium with permittivity of ϵ and permeability μ is:

Detailed Solution for RRB JE EC CBT Test 1 - Question 17

The characteristic impedance of a wave travelling in a lossy medium is given by

Put σ = 0 (free space and lossless medium)

RRB JE EC CBT Test 1 - Question 18

Which among the following indicates the orientation of sub-shells in an atom?

Detailed Solution for RRB JE EC CBT Test 1 - Question 18
• The quantum number defines an electron completely in an atom.
• There are four types of quantum number - Principal Quantum Number, Azimuthal Quantum Number, Magnetic Quantum Number and Spin Quantum Number.
• Principal Quantum Number describes the size, shape and energy of the shell to which an electron belongs whereas Azimuthal Quantum Number determines the shape of the electron cloud and the number of sub-shells in a shell.
• Magnetic Quantum Number determines the orientation of sub-shells whereas the spin quantum number represents the direction of the electron spin.
RRB JE EC CBT Test 1 - Question 19

Which of the following is used to write database schema?

Detailed Solution for RRB JE EC CBT Test 1 - Question 19

A database schema is the skeleton structure that represents the logical view of the entire database. SQL commands can be used to create a database schema.

SQL commands are divided into four subgroups, DDL, DML, DCL, and TCL.

DDL (Data Definition Language) statements are used for creating and defining the Database Schema.

Examples: CREATE, ALTER, DROP statements

While DML (Data Manipulation Language) statements are used for managing data within the Database.

Examples: SELECT, UPDATE, INSERT statements

DCL (Data Control Language) which includes commands that are mostly concerned with rights, permissions and other controls of the database system.

Example: GRANT, REVOKE

TCL (Transaction Control Language) deals with a transaction within a database.

Example: COMMIT, ROLLBACK

RRB JE EC CBT Test 1 - Question 20

Which of the following is not a greenhouse gas?

Detailed Solution for RRB JE EC CBT Test 1 - Question 20

Greenhouse effect

• It occurs due to the increase in the percentage of carbon dioxide in the atmosphere
• It absorbs the solar rays and energy of the sun due to which the temperature on the earth increases and natures balance gets disturbed
• Our vehicles and industries are continuously increasing the amount of carbon dioxide in the atmosphere

Global Warming

• Increase in average temperature of the earth surface due to the greenhouse effect is called global warming
• It also refers to the increase in average temperature of the air and sea at earth's surface

Green House Gases (GHG):
The major greenhouse gases are

• Water vapour - causes about 36% - 70% of the greenhouse effect
• Carbon dioxide (CO2) which causes 9 - 26%
• Methane (CH4) causes 4 - 9% and ozone (O3)

So Ethane is not a greenhouse gas

RRB JE EC CBT Test 1 - Question 21

Internet Explorer is a __________.

Detailed Solution for RRB JE EC CBT Test 1 - Question 21

Web browser: A browser is a software application used to locate, retrieve and display content of Web pages, images, video and other files. The browser contacts the Web server and requests information and Web server sends the information back to the Web browser which displays the results on the computer.

Some commonly used web browsers are:

• Internet Explorer: Internet Explorer (IE) is a web browser from Microsoft
• Firefox: Firefox is a free, open-source web browser from Mozilla
• Opera: Opera is a free, fast, small and standard - compliant web browser developed by the Opera Software company
• Netscape: Netscape was the first commercial web browser
RRB JE EC CBT Test 1 - Question 22

Detailed Solution for RRB JE EC CBT Test 1 - Question 22

A Threat is any circumstance or event with the potential to cause harm to the system or activity in the form of destruction, disclosure, and modification of data, or denial of service. A threat is a potential for harm.

Some of the common terms associated with threats and their description are as follows:

• Malware: A collective term for malicious software, such as viruses, worms and trojans; designed to infiltrate systems and information for criminal, commercial or destructive purposes.
• Phishing: A form of social engineering, involving the sending of legitimate-looking emails aimed at fraudulently extracting sensitive information from recipients, usually to gain access to systems or for identity theft.
• Spam: Unsolicited email sent in bulk to many individuals, usually for commercial gain, but increasingly for spreading malware.

Spoofing: A spoofing attack is when a malicious party impersonates another device or user on a network in order to launch attacks against network hosts, steal data, spread malware, or bypass access controls. There are several different types of spoofing attacks that malicious parties can use to accomplish this. They are IP Address Spoofing Attacks, ARP (Address Resolution Protocol) Spoofing Attacks, DNS Server Spoofing Attacks, etc.

software bug is an error, flaw, failure or fault in a computer program or system that causes it to produce an incorrect or unexpected result, or to behave in unintended ways.

RRB JE EC CBT Test 1 - Question 23

Which of the following is used to provide adequate strength to optical fibres to prevent them from collapsing during installation?

Detailed Solution for RRB JE EC CBT Test 1 - Question 23

The function of different materials in an optical fibre are:

Protect cable jacket from damage during shrinking of heat shrink sleeves.

• Stainless steel channel under clip:

The stainless-steel channel and under clip is used to close the heat shrink sleeves before shrinking.

• Aluminium canister – Finger coated:

Provide adequate structural strength to avoid collapsing during installation.

• Emery strip

The emery strip is used for surface preparation of cable with PVC/Polyethylene sheath.

RRB JE EC CBT Test 1 - Question 24

In controlled rectifiers, the nature of load current, i.e. whether load current is continuous or discontinuous

Detailed Solution for RRB JE EC CBT Test 1 - Question 24
• In controlled rectifiers, the nature of load current, i.e. whether load current is continuous or discontinuous depends both on the type of load and firing angle delay
• The average load current supplied by a thyristor depends on firing angle
RRB JE EC CBT Test 1 - Question 25

Where has the second India-Myanmar bilateral Army exercise named 'IMBEX 2018-19' commenced on 14 January 2019?

Detailed Solution for RRB JE EC CBT Test 1 - Question 25
• The second India-Myanmar bilateral Army exercise named 'IMBEX 2018-19' commenced at Chandimandir military station in Haryana on 14 January 2019.
• The aim of this joint training event is to train the Myanmar delegation for participation in UN peacekeeping operations.
• The exercise includes participation of 15 officers from Myanmar Army and 15 officers from Indian Army
RRB JE EC CBT Test 1 - Question 26

When a material is placed in a magnetic field, the induced magnetic field in the material is in the same direction as an applied magnetic field. The material is:

Detailed Solution for RRB JE EC CBT Test 1 - Question 26

Properties of Diamagnetic, Paramagnetic and ferromagnetic materials placed in the magnetic field is shown in the table

RRB JE EC CBT Test 1 - Question 27

Compared to signal ended amplifier, a pushpull amplifier offers

Detailed Solution for RRB JE EC CBT Test 1 - Question 27

Due to the Class B operation, their collector efficiency is quite high.

• They give more AC output power per device
• Distortion free output is obtained
• Output Transformer used for push-pull amplifier circuit are lighter, smaller and less expensive than the transformers of comparable quality that are used in single-ended circuits
• In the core of the output transformer, the DC components for output currents of the two devices oppose each other magnetically which eliminates the tendency of the core to saturate
RRB JE EC CBT Test 1 - Question 28

In IT networking, which of the following device is used in physical layer?

Detailed Solution for RRB JE EC CBT Test 1 - Question 28

In telecommunications, a repeater is an electronic device that receives a signal and retransmits it. Repeaters are used to extend transmissions so that the signal can cover longer distances or be received on the other side of an obstruction.

RRB JE EC CBT Test 1 - Question 29

Which of the following is not a C library function?

Detailed Solution for RRB JE EC CBT Test 1 - Question 29

The C Library functions are inbuilt functions in C programming.

The prototype and data definitions of the functions are present in their respective header files and must be included in the program to access them.

Predefined functions:

hello() is a user-defined function.

RRB JE EC CBT Test 1 - Question 30

In an AC circuit, the ratio of kW/kVA represents

Detailed Solution for RRB JE EC CBT Test 1 - Question 30

Power factor: It is the ratio between true power and apparent power
Power factor = kW/kVA

Form factor: It is the ratio of the RMS (root mean square) value to the average value.

Load factor: It is defined as the ratio of the average load over a given period to the maximum demand (peak load) occurring in that period.

Diversity factor: It is the ratio of sum of individual maximum demand to maximum demand on power station

RRB JE EC CBT Test 1 - Question 31

Which of the following is NOT a mouse usage?

Detailed Solution for RRB JE EC CBT Test 1 - Question 31

A computer mouse is an input device that is most often used with a personal computer. Moving a mouse along a flat surface can move the on-screen cursor to different items on the screen. Items can be moved or selected by pressing the mouse buttons (called clicking). The mouse has two buttons, the left button, and right button, with a scroll wheel in between the two.

Use of a mouse:

• Move the mouse cursor - The primary function is to move the mouse pointer on the screen.
• Open or execute a program - Once you've moved the pointer to an icon, folder, or other object clicking or double-clicking that object opens the document or executes the program.
• Select - A mouse also allows you to select text or a file or highlight and select multiple files at once.
• Drag-and-drop - Once something is selected, it can also be moved using the drag-and-drop method.
• Hover - Moving the mouse cursor over objects with additional hover information can help discover the function of each object on the screen. For example, hover the mouse over the hover link to see an example.
• Scroll - When working with a long document, or viewing a long web page, you may need to scroll up or down. To scroll, use the mouse wheel, or click and drag the scroll bar.
RRB JE EC CBT Test 1 - Question 32

Which virus infects the important files of MS word?

Detailed Solution for RRB JE EC CBT Test 1 - Question 32

A virus is a program that can infect other programs by modifying them to include a possibly evolved copy of itself.

Some of the common types of viruses are:

• Boot Sector Virus: A boot sector virus displaces the boot record and copies itself to the boot sector i.e. where the program to boot the machine is stored.
• File Virus: A file virus generally attacks executable files.
• Macro Virus: The virus infects an important file of MS word. As soon as the application is opened the virus gets activated. It damages the formatting of documents and may not even allow the editing or saving of documents
• Trojan Horse: It is a code hidden in games or spreadsheets. Its main objective is to cause harm to the data. They can create a bad sector on the disk, destroy file allocation tables and cause the system to hang.
• Worm: It is a program capable of replicating itself on a computer network. It travels from one computer to another across communication links. They generally disrupt the routine services.
RRB JE EC CBT Test 1 - Question 33

When a bipolar junction transistor is operating in the saturation mode, which one of the following statements is TRUE about the state of its collector-base (CB) and the base-emitter (BE) junctions?

Detailed Solution for RRB JE EC CBT Test 1 - Question 33

In Bipolar transistor, saturation mode occurs when
1. Collector – base (CB) is forward biased.
2. Base-emitter (BE) is also forward biased.
Hence, for the saturation condition, bath the junction should be in forward-bias, as shown in the figure below.

RRB JE EC CBT Test 1 - Question 34

Which law of thermodynamics defines the concept temperature?

Detailed Solution for RRB JE EC CBT Test 1 - Question 34

The Zeroth law of thermodynamics defines temperature. It states that “If two systems are in thermal equilibrium with the third system, then they are in thermal equilibrium with each other.”

Zeroth law – concept of temperature
First law – concept of internal energy
Second law – concept of entropy

RRB JE EC CBT Test 1 - Question 35

Which city is called as the Pittsburgh of India?

Detailed Solution for RRB JE EC CBT Test 1 - Question 35
• Jamshedpur is known as the Steel City of India or Pittsburgh of India for being rich in minerals.
• It is a home to many industries like Tata Motors, Tata Steels, Usha Martin Industries, Steel & Wire Products, Tata Pigments, Tayo Rolls Limited, and many other assets.
• This city is also known as the Tatanagar.
RRB JE EC CBT Test 1 - Question 36

When two liquids do not mix with each other to form a solution, what is it called?

Detailed Solution for RRB JE EC CBT Test 1 - Question 36
• The two liquids that can't dissolve in each other or the two liquids in which diffusion can't takes place are called immiscible liquids. They can’t form homogeneous mixtures.For example- Water and oil.
• When two liquids can be mixed to form homogeneous mixtures they are called miscible liquids.

For example- Alcohol and water.
Extra Information:

RRB JE EC CBT Test 1 - Question 37

The simplified Boolean expression for XYZ + XY’Z + XYZ’ is:

Detailed Solution for RRB JE EC CBT Test 1 - Question 37

XYZ + XY’Z + XYZ’
XZ (Y + Y’) + XYZ’
XZ + XYZ’
X (Z + Y Z’)
X (Z + Y) (Z + Z’)
X (Z + Y)

RRB JE EC CBT Test 1 - Question 38

A logic gate acts as an inverter when one of its input is connected to logic high, the gate is

Detailed Solution for RRB JE EC CBT Test 1 - Question 38

The truth table is shown below:

Thus, in case of NAND and EX OR gates when one input is connected to logic High, the other input is inverted.

RRB JE EC CBT Test 1 - Question 39

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

Detailed Solution for RRB JE EC CBT Test 1 - Question 39

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 1 - Question 40

Which one of the following places of Indus Valley Civilization was situated on the bank of Ravi River?

Detailed Solution for RRB JE EC CBT Test 1 - Question 40

RRB JE EC CBT Test 1 - Question 41

__________ is a telecommunications network or computer network that extends over a large geographical distance.

Detailed Solution for RRB JE EC CBT Test 1 - Question 41

A wide area network (WAN) is a telecommunications network or computer network that extends over a large geographical area, generally having a radius of more than 1 km. Wide area networks are often established with leased telecommunication circuits.

A Uniform Resource Locator (URL), colloquially termed a web address, is a reference to a web resource that specifies its location on a computer network and a mechanism for retrieving it. A URL is a specific type of Uniform Resource Identifier (URI), although many people use the two terms interchangeably. URLs occur most commonly to reference web pages (http), but are also used for file transfer (ftp), email (mailto), database access (JDBC), and many other applications.

Simple Mail Transfer Protocol (SMTP) is an Internet standard for electronic mail (email) transmission.

JavaScript is a high - level, dynamic, untyped, interpreted run - time language. Alongside HTML and CSS, JavaScript is one of the three core technologies of World Wide Web content production.

RRB JE EC CBT Test 1 - Question 42

The functions of connecting a resistor in series with a gate-cathode circuit and a Zener-diode across gate-cathode circuit are, respectively, to protect the gate circuit from

Detailed Solution for RRB JE EC CBT Test 1 - Question 42
• The functions of connecting a resistor in series with a gate-cathode circuit to protect the gate circuit from overcurrent
• The functions of connecting a Zener diode across the gate-cathode circuit to protect the gate circuit from overvoltage
RRB JE EC CBT Test 1 - Question 43

Who has won the Men's singles final​ in the US Open Tennis 2018?

Detailed Solution for RRB JE EC CBT Test 1 - Question 43
• In the US Open Tennis, Novak Djokovic of Serbia won the Men's singles final.
• He defeated Juan Martin del Potro of Argentina. It was Djokovic's 14th Grand Slam title and the third US Open title.
• With this win, he has equaled Pete Sampras's mark of 14 Grand Slams.
RRB JE EC CBT Test 1 - Question 44

The minimum dimension of copper, earth plate as per ISI code is

Detailed Solution for RRB JE EC CBT Test 1 - Question 44

Minimum dimension of copper earth plate = 60 cm × 60 cm × 3.18 mm
Minimum dimension of G.I earth plate = 60 cm × 60 cm × 6.38 mm

RRB JE EC CBT Test 1 - Question 45

Programs stored in which of the following memories can’t be erased?

Detailed Solution for RRB JE EC CBT Test 1 - Question 45

ROM is a non-volatile memory. Its contents are retained even after the power is switched off. ROM stores the program required to initially boot the computer. It only allows for reading.

RRB JE EC CBT Test 1 - Question 46

Which browser is an inbuilt browser in windows?

Detailed Solution for RRB JE EC CBT Test 1 - Question 46

Web browser

• A browser is a software application used to enable computers users to locate and access web pages
• Browser translates the basic HTML code that allows us to see image, text video and listen to audios on the website, along with hyperlinks that let us travel to different web pages
• The Web utilizes browsers, such as Internet Explorer or Firefox, to access web documents called web pages that are linked to each other via hyperlinks

Some commonly used web browsers are:

• Internet Explorer: Internet Explorer (IE) is a web browser from Microsoft
• Firefox: Firefox is a free, open-source web browser from Mozilla
• Opera: Opera is a free, fast, small and standard - compliant web browser developed by the Opera Software company
• Netscape: Netscape was the first commercial web browser
RRB JE EC CBT Test 1 - Question 47

Which of the following is the unity follower circuit

Detailed Solution for RRB JE EC CBT Test 1 - Question 47

The unity follower circuit is the circuit having unit gain.

In the above circuit, V- = V+ = Vi
Hence Vo = V(which is voltage follower)

RRB JE EC CBT Test 1 - Question 48

Where will the deleted files be stored?

Detailed Solution for RRB JE EC CBT Test 1 - Question 48

In computing, the Trash (also known as the Recycle Bin in Windows) is the temporary storage for files that have been deleted in a file manager by the user, but not yet permanently erased from the file system.

Typically, a recycle bin is presented as a special file directory to the user, allowing the user to browse deleted files, undelete those that were deleted by mistake, or delete them permanently (either one by one, or by the "Empty Trash" function).

RRB JE EC CBT Test 1 - Question 49

Convert 1268 to decimal:

Detailed Solution for RRB JE EC CBT Test 1 - Question 49

To convert octal to decimal, multiply each position by its weight and add:
1268 = 1 × 82 + 2 × 81 + 6 × 80 = 86

RRB JE EC CBT Test 1 - Question 50

Which of these poets were awarded 'Saraswati Samman 2017' on 22 January 2019?

Detailed Solution for RRB JE EC CBT Test 1 - Question 50
• Gujarati poet Sitanshu Yashashchandra was awarded 'Saraswati Samman 2017' on 22 January 2019.
• He was awarded for his poetry collection in Gujarati named 'Vakhar'.
• The award was instituted by K.K.Birla foundation.
• The award is given every year to an outstanding work of an Indian citizen published during the last 10 years in any of the languages mentioned in Schedule 8 of the constitution.
RRB JE EC CBT Test 1 - Question 51

Which of the following multiple access techniques are used by second generation cellular systems?

Detailed Solution for RRB JE EC CBT Test 1 - Question 51

1st Generation – used FDMA/FDD techniques
Voice only signals
Analogue Cellular Phones

NMT, AMPS

2nd Generation- used TDMA/FDD and CDMA/FDD
- Voice and data signals
- GSM CDMA TDMA
2.5 Generation – Enhance 2 G
- Higher data rates
- GPRS, EDGE

3rd Generation – Voice, Data and Video Signals
Video, Telephony/Internet surfing
3 G, W-CDMA, UMTS

4th Generation – Enhanced 3G/Interoperability protocol

• High speed and IP based
• 4G, Mobile IP
RRB JE EC CBT Test 1 - Question 52

A radar transmitting has a pulse repetition frequency of 1500 PPS and a pulse width of 1 microsecond. The duty cycle is:

Detailed Solution for RRB JE EC CBT Test 1 - Question 52

For a RADAR the duty cycle is given by:
Duty cycle = Pulse width × pulse repetition frequency
D = 1 × 10-6 × 1500 = 0.0015

RRB JE EC CBT Test 1 - Question 53

The adverse effect(s) of acid rain is(are)

Detailed Solution for RRB JE EC CBT Test 1 - Question 53

When the quantity of acids in the raining water is more than the average, then such rain is called 'Acid rain'.

We are aware that normally rainwater has a pH of 5.6.  When the pH of the rainwater drops below 5.6, it is called acid rain.

Acid rain refers to the ways in which acid from the atmosphere is deposited on the earth’s surface. Oxides of nitrogen and sulphur which are acidic in nature can be blown by wind along with solid particles in the atmosphere and finally settle down either on the ground as dry deposition or in water, fog and snow as wet deposition.

Acid rain is a byproduct of a variety of human activities that emit the oxides of sulphur and nitrogen in the atmosphere. As mentioned earlier, burning of fossil fuels (which contain sulphur and nitrogenous matter) such as coal and oil in power stations and furnaces or petrol and diesel in motor engines produce sulphur dioxide and nitrogen oxides.

SO2 and NO2 after oxidation and reaction with water are major contributors to acid rain because polluted air usually contains particulate matter that catalyses the oxidation.

2SO2 (g) + O2 (g) + 2H2O (l) → 2H2SO4 (aq)
4NO2 (g) + O2 (g)+ 2H2O (l) → 4HNO3 (aq)

The bad effects of acid rain

• When acid rain falls and flows as groundwater to reach rivers, lakes etc, it affects plants and animal life in the aquatic ecosystem
• Acid rain is harmful to agriculture, trees and plants as it dissolves and washes away nutrients needed for their growth
• It causes respiratory ailments in human beings and animal
• It may also cause corrosion in many buildings bridges, monuments, fencing etc
• It causes irritation in the eyes and skin of human beings
• This rain reduces the lustre of the metals too
• Acid rain damages buildings and other structures made of stone or metal
• The Taj Mahal in India has been affected by acid rain
RRB JE EC CBT Test 1 - Question 54

Which of the following fuels causes minimum environmental pollution?

Detailed Solution for RRB JE EC CBT Test 1 - Question 54

Hydrogen fuel is a zero-emission fuel when burned with oxygen (if one considers water not as an emission) or used in a contained cell (allowing to react galvanically) also capable of 'reversing' the reaction if needed.

RRB JE EC CBT Test 1 - Question 55

The total number of hardware interrupts present in 8085 microprocessor are

Detailed Solution for RRB JE EC CBT Test 1 - Question 55

8085 microprocessor contains,

When microprocessors receive interrupt signals through pins (hardware) of the microprocessor, they are known as Hardware Interrupts

Five hardware interrupts: TRAP, RST 5.5, RST 6.5, RST 7.5 and INTR

Software Interrupts are those which are inserted in between the program, these are mnemonics of the microprocessor.

Eight software interrupts: RST 0 to RST 7

RRB JE EC CBT Test 1 - Question 56

Which among the following glasses can cut off the UV rays?

Detailed Solution for RRB JE EC CBT Test 1 - Question 56
• Crooked Glass can cut off the UV rays.
• It is a special type of glass which contains Cerium Oxide [CeO2].
• It is used in making sunglasses.
RRB JE EC CBT Test 1 - Question 57

As a result of greenhouse effect, the average temperature of the earth’s atmosphere is gradually increasing. This is called _____.

Detailed Solution for RRB JE EC CBT Test 1 - Question 57

As a result of the greenhouse effect, the average temperature of the earth’s atmosphere is gradually increasing. This is called Global warming. The exchange of incoming and outgoing radiation that warms the surface of Earth is known as the greenhouse effect. The greenhouse gases include carbon dioxide, methane, water vapors, nitrous oxide, and other gases.

RRB JE EC CBT Test 1 - Question 58

Which layer 1 devices can be used to enlarge the area covered by a single LAN segment?
1. Switch
2. NIC
3. Hub
4. Repeater
5. RJ45 transceiver

Detailed Solution for RRB JE EC CBT Test 1 - Question 58

Physical layer (Layer 1): Hubs, Repeaters

Data-link layer (Layer 2): Bridges, Modems, Network cards, 2-layer switches.

Network layer (Layer 3): Routers, 3-layer switches.

Transport layer (Layer 4): Gateways, Firewalls.

Session layer (Layer 5): Gateways, Firewalls, PC’s.

Presentation layer (Layer 6): Gateways, Firewalls, PC’s.

Application layer (Layer 7): Gateways, Firewalls, all end devices

RRB JE EC CBT Test 1 - Question 59

A program that provides software interface to hardware devices is called _________.

Detailed Solution for RRB JE EC CBT Test 1 - Question 59

In computing, a device driver (commonly referred to simply as a driver) is a computer program that operates or controls a particular type of device that is attached to a computer. A driver provides a software interface to hardware devices, enabling operating systems and other computer programs to access hardware functions without needing to know precise details of the hardware being used.

RRB JE EC CBT Test 1 - Question 60

The disadvantage of constant current battery charging method is

Detailed Solution for RRB JE EC CBT Test 1 - Question 60

In constant current charging method, the battery is supplied with constant current throughout its charging period. Through this method, the charging is fast initially but slows down near high values of battery charge.

RRB JE EC CBT Test 1 - Question 61

The address size of 8086 microprocessor is

Detailed Solution for RRB JE EC CBT Test 1 - Question 61

For 8085 microprocessor,
Data or word size = 8bit
For 8086 microprocessor,
Data or word size = 16bit

RRB JE EC CBT Test 1 - Question 62

In C++ clrscr() and getch() are predefined function in _______.

Detailed Solution for RRB JE EC CBT Test 1 - Question 62

In C++, clrscr() used to clear the console screen. It is a predefined function which clears the data from console.

In C++, getch() is used to catch a character from the keyboard. The getch() function reads a single character from the keyboard but does not show on the screen.

clrscr() and getch()  both are predefined function in conio.h.

RRB JE EC CBT Test 1 - Question 63

Generation in computer terminology is

Detailed Solution for RRB JE EC CBT Test 1 - Question 63

The generations of computers are characterized by a major technological development that fundamentally changed the way computers operate, resulting in smaller, cheaper, more powerful and more efficient and reliable devices.

The various generations of computers are listed below:

RRB JE EC CBT Test 1 - Question 64

What is the IUPAC name of sec-Butyl chloride?

Detailed Solution for RRB JE EC CBT Test 1 - Question 64
• The IUPAC name of sec-Butyl chloride is 2-Chlorobutane.​

RRB JE EC CBT Test 1 - Question 65

Retrace period for an ideal sawtooth waveform is

Detailed Solution for RRB JE EC CBT Test 1 - Question 65

The time during which the output increases linearly is called as sweep time (TS) and the time taken for the signal to get back to its initial value is called as restoration time or fly-back time or retrace time (Tr). For ideal sawtooth waveform retrace period should be zero seconds.

RRB JE EC CBT Test 1 - Question 66

What does WLAN stand for?

Detailed Solution for RRB JE EC CBT Test 1 - Question 66

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.

WLAN, which stands for 'Wireless Local Area Network', is when a mobile user connects to a local area network via a wireless connection.

RRB JE EC CBT Test 1 - Question 67

C contains two Special Pointer operators:

Detailed Solution for RRB JE EC CBT Test 1 - Question 67

In C, &variable_name will hold the address of a variable in the memory, where & is commonly called the reference operator.
e.g. for int p, &p stores its address in the memory.

Pointers is a variable that stores or points the address of another variable. It is used to allocate memory dynamically i.e. at run time.

& symbol is used to get the address of the variable while the * symbol is used to get the value of the variable that the pointer is pointing to.

RRB JE EC CBT Test 1 - Question 68

Sewage waste is a

Detailed Solution for RRB JE EC CBT Test 1 - Question 68

According to nature, pollutants can be classified into Non-degradable pollutants and Bio - degradable pollutants.

Those pollutants which cannot be broken down into simpler, harmless substances in nature.

DDT, plastics, polythene, bags, insecticides, pesticides, mercury, lead, arsenic, metal articles like aluminium cans, synthetic fibres, glass objects, iron products and silver foils are nonbiodegradable pollutants. (Tables)

Those pollutants which can be broken down into simpler, harmless substances in nature.

Sewage waste, domestic waste, etc. are the bio-degradable waste.

RRB JE EC CBT Test 1 - Question 69

The patterns used to measure phase and frequency with a cathode ray oscilloscope are called

Detailed Solution for RRB JE EC CBT Test 1 - Question 69
• When horizontal deflection plates and vertical deflection plates of CRO (Cathode Ray Oscilloscope) are connected to two sinusoidal voltages, the patterns appear at CRO screen are called the Lissajous pattern
• The Lissajous pattern obtained in a CRO depends upon frequency, amplitude and phase relationship
• The patterns used to measure phase and frequency with a cathode ray oscilloscope are called Lissajous pattern
RRB JE EC CBT Test 1 - Question 70

With which game is the 'Agha Khan Cup' associated?

Detailed Solution for RRB JE EC CBT Test 1 - Question 70

‘Agha Khan Cup’ is associated with the game of Hockey whereas Agha Khan Gold Cup is associated with Football.

RRB JE EC CBT Test 1 - Question 71

Where is the largest population of Bhil Tribe found in India?

Detailed Solution for RRB JE EC CBT Test 1 - Question 71

The Bhil are an indigenous tribe in the Kolarian group and were the earliest settlers in India. According to the 2011 Census of India, Bhil is the most populous tribe in Madhya Pradesh with a total population of 4,618,068, constituting 37.7 per cent of the total ST population.

RRB JE EC CBT Test 1 - Question 72

If x denotes the distance in p and n regions in a p-n junction diode with x > 0 denoting n region and x < 0 denoting p region and x = 0 is the junction. Then at thermal equilibrium in a p-n junction

Detailed Solution for RRB JE EC CBT Test 1 - Question 72
• At equilibrium, the Fermi level of p and n semiconductor regions are perfectly aligned
• There is no variation of Fermi level and no net flow of current

RRB JE EC CBT Test 1 - Question 73

The process of decomposing organic waste in the presence of air is termed as

Detailed Solution for RRB JE EC CBT Test 1 - Question 73

Incineration is a waste treatment process that involves the combustion of organic substances contained in waste materials. Incineration and other high-temperature waste treatment systems are described as "thermal treatment". Incineration of waste materials converts the waste into ash, flue gas and heat means in the presence of air.

RRB JE EC CBT Test 1 - Question 74

Consider the following registers:
a. A and B registers
b. B and C registers
c. D and E registers
d. H and L registers

Q. Which of these 8-bit registers of 8085 microprocessor can be paired together to make a 16-bit register?

Detailed Solution for RRB JE EC CBT Test 1 - Question 74
• The 8085/8080A has six general-purpose registers to store 8-bit data
• These are identified as B, C, D, E, H, and L
• They can be combined as register pairs - BC, DE, and HL - to perform some 16-bit operations
RRB JE EC CBT Test 1 - Question 75

When a UJT is used for triggering an SCR, the waveshape of the voltage obtained from the UJT circuit is a

Detailed Solution for RRB JE EC CBT Test 1 - Question 75

The unijunction transistor is a solid-state three-terminal device that can be used in gate pulse, timing circuits and trigger generator applications to switch and control both thyristors and triacs for AC power control type applications. When a UJT is used for triggering an SCR, the wave shape of the voltage obtained from the UJT circuit is a saw-tooth wave.

RRB JE EC CBT Test 1 - Question 76

The correct sequence of different layers of the atmosphere from the surface of the Earth upwards is

Detailed Solution for RRB JE EC CBT Test 1 - Question 76

Structure of the atmosphere
The atmosphere is divided into five layers starting from the earth's surface:

1. Troposphere (0 - 18 km): This is the most important layer of the atmosphere. The air breath exists here. All the weather changes like rainfall, fog, and hailstorm occur in this layer.
2. Stratosphere (18 - 50 km): It is free from clouds which makes it the most ideal layer for flying Aeroplanes. It contains a layer of ozone gas which protects from the harmful effect of the sun rays.
3. Mesosphere (50 - 85 km): It is the third layer of the atmosphere. Temperature drops to about -95°C.
4. Thermosphere (85 - 500 km): In this layer, the temperature rises very rapidly with increasing height. The ionosphere is a part of this layer. It helps in radio transmission.
5. Exosphere (500 - 1600 km): The uppermost layer of the atmosphere is called exosphere. It is very thin air. Temperature is very high due to direct solar radiation. Light gases like Helium and Hydrogen float into space from here.

The Exosphere is the uppermost layer of the atmosphere.

RRB JE EC CBT Test 1 - Question 77

Q. The correct order of conversion time (T) of the ADCs shown above is –

Detailed Solution for RRB JE EC CBT Test 1 - Question 77

For n-bit ADC of different type the conversion times are as follows -
Counter type (TA) = 2TCLK
Dual slop (TB) = 2n+1 TCLK
SAR type (TC) = n TCLK
Flash type (TD) = TCLK

RRB JE EC CBT Test 1 - Question 78

A transmitter radiates 9 kW without modulation and 10.125 kW after modulation. Determine the modulation index.

Detailed Solution for RRB JE EC CBT Test 1 - Question 78

We have, carrier power, PC = 9kW
Modulated signal power, PT = 10.125kW
For modulation index,

RRB JE EC CBT Test 1 - Question 79

A transmission line is distortionless if,

Detailed Solution for RRB JE EC CBT Test 1 - Question 79

A transmission line is distortionless if  R/L = G/C
Rewriting this we have, LG = RC
Note:
If R/L = G/C then phase velocity is given by
the phase velocity is independent of frequency hence the transmission line is distortionless.

RRB JE EC CBT Test 1 - Question 80

The virtual ground concept in op-amp is valid for

Detailed Solution for RRB JE EC CBT Test 1 - Question 80
• Virtual ground concept is valid for only Negative feedback systems
• Negative feedback systems decrease the differential input voltage between and non-inverting terminals

When difference becomes zero, the voltage at two terminals become equal, which is a virtual ground concept

RRB JE EC CBT Test 1 - Question 81

In the given figure if input voltage V= -1V then output voltage V0 is:

Detailed Solution for RRB JE EC CBT Test 1 - Question 81

When Vi = -1 V then using a virtual ground

V- = -1 V

This will turn off the diode, hence there will be no negative feedback and no virtual ground
Thus Vo = 0 V

RRB JE EC CBT Test 1 - Question 82

What is the process of slow cooling of hot glass called?

Detailed Solution for RRB JE EC CBT Test 1 - Question 82
• Annealing is one of the major processes in the manufacture of glass.
• It is a controlled slow cooling process of heat treatment of glass.
• It helps in strengthening the glass and relieving the stress.
RRB JE EC CBT Test 1 - Question 83

When warm air rises up and cold air from the surrounding areas rushes in to fill its place then this sets up ________ in air.

1. Conduction
2. Convection
4. Agitation
Detailed Solution for RRB JE EC CBT Test 1 - Question 83

When warm air rises up and cold air from the surrounding areas rushes in to fill its place then this sets up convection in air.

• When warm air rises, the air pressure at that place gets lowered. The cold air from the surrounding areas rushes in to fill its place. This sets up convection currents in the air.
• Wind currents are generated due to uneven heating on the earth.
• Convection is the process by which the transmission of heat takes place through a substance from one point to another due to actual bodily movement of heated particles of the substance.
RRB JE EC CBT Test 1 - Question 84

The combinational logic circuit shown in the given figure has an output Q which is:

Detailed Solution for RRB JE EC CBT Test 1 - Question 84

(using the relation
(using the relation
= A+B+C

RRB JE EC CBT Test 1 - Question 85

What operations can be done on linear data structure?

Detailed Solution for RRB JE EC CBT Test 1 - Question 85

A data structure is a data organization, management and storage format that enables efficient access and modification.

A data structure can be divided into two categories:

1. Linear data structure

A data structure is said to be linear if its elements form a sequence or a linear list.
Examples: Array, Linked List, Stacks, Queue

On a linear data structure, one can do insertion, deletion, Traversal, Sorting, merging, Search.​

2. Nonlinear data structure

It arranges the data in sorted order and there exists a relationship between the data elements.
Examples: Tree, Graph

RRB JE EC CBT Test 1 - Question 86

Light can travel in vacuum but not sound, because ________.

Detailed Solution for RRB JE EC CBT Test 1 - Question 86
• Light can travel in a vacuum because the light is electromagnetic in nature which requires no medium as electric fields and magnetic fields constantly generate each other as the wave propagates.
• Sound waves require a medium to travel. The speed of sound is faster in solid materials, slower in liquids and slowest in gases.
• The speed of light in a vacuum is commonly given the symbol c. It is a universal constant that has the value c = 3 x 108 m/second.
RRB JE EC CBT Test 1 - Question 87

The Lissajous pattern on a CRO screen is shown in the given figure: the frequency ratio of the vertical signal to the horizontal one is:

Detailed Solution for RRB JE EC CBT Test 1 - Question 87

RRB JE EC CBT Test 1 - Question 88

In satellite communication, multiple repeaters are known as:

Detailed Solution for RRB JE EC CBT Test 1 - Question 88

A transponder receives and transmits radio signals at a prescribed frequency range. After receiving the signal a transponder will at the same time broadcast the signal at a different frequency. The term is a combination of the words transmitter and responder.

RRB JE EC CBT Test 1 - Question 89

Which among the following is the capital of Finland?

Detailed Solution for RRB JE EC CBT Test 1 - Question 89

Helsinki is the capital of Finland.

RRB JE EC CBT Test 1 - Question 90

In frequency modulation, the modulation index is proportional to

Detailed Solution for RRB JE EC CBT Test 1 - Question 90

For FM, modulation index

RRB JE EC CBT Test 1 - Question 91

The OPAMP circuit shown below  represents a

Detailed Solution for RRB JE EC CBT Test 1 - Question 91

At f = 0 → XL = 2πfL = 0 → inductor is short circuited
the capacitor is open circuited

∴ circuit passes low frequencies
At f = ∞ inductor is open circuited and the capacitor is short-circuited → Vout = 0
∴ the circuit does not pass high frequencies. So the given circuit acts as a low pass filter

RRB JE EC CBT Test 1 - Question 92

Which of the following is not a linear data structure?

Detailed Solution for RRB JE EC CBT Test 1 - Question 92

A data structure is a data organization, management and storage format that enables efficient access and modification.

A data structure can be divided into two categories:

1. Linear data structure

A data structure is said to be linear if its elements form a sequence or a linear list.
Examples: Array, Linked List, Stacks, Queue

2. Nonlinear data structure

It arranges the data in sorted order and there exists a relationship between the data elements.
Examples: Tree, Graph

RRB JE EC CBT Test 1 - Question 93

Which one of the following is not a committee dedicated to the establishment of data communication standards?

Detailed Solution for RRB JE EC CBT Test 1 - Question 93

An Internet standard is a thoroughly tested specification that is useful to and adhered to by those who work with the Internet. It is a formalized regulation that must be followed. There is a strict procedure by which a specification attains Internet standard status. A specification begins as an Internet draft. An Internet draft is a working document (a work in progress) with no official status and a 6month lifetime. Upon recommendation from the Internet authorities, a draft may be published as a Request for Comment (RFC). Each RFC is edited, assigned a number, and made available to all interested parties. RFCs go through maturity levels and are categorized according to their required level.

RRB JE EC CBT Test 1 - Question 94

Which flag is not affected by the DCR B instruction in 8085?

Detailed Solution for RRB JE EC CBT Test 1 - Question 94
• INR and DCR instructions affect all flags except carry flag
• ADI instruction affects all flags
• No flags are affected by INX and DCX instructions
RRB JE EC CBT Test 1 - Question 95

Which of the following I-V curves among ‘a’ and ‘b’ for Solar cell corresponds to the I-V curve under illumination condition.

Detailed Solution for RRB JE EC CBT Test 1 - Question 95

a. without illumination, under normal operation the current is dark current
b. under illumination, under no-load operation, the voltage is open circuit voltage Voc
Under short circuit operation, the current shown is the short circuit current.

RRB JE EC CBT Test 1 - Question 96

A certain diff. amplifier has a differential voltage gain of 2000 and a common mode gain of 0.2. The CMMR is decibels (dB) is:

Detailed Solution for RRB JE EC CBT Test 1 - Question 96

Given that, differential voltage gain (Ad) = 2000
Common mode gain (Ac) = 0.2
Common mode rejection ratio (CMRR) is given by,

RRB JE EC CBT Test 1 - Question 97

If the plates of a capacitor are brought closer to each other, what will be the effect on capacitance?

Detailed Solution for RRB JE EC CBT Test 1 - Question 97
• If the two plates are brought closer to each other, the capacitance of the system will increase.
• This can be proved from the expression, C = (ε0A)/d
• Where ε0 is the electric constant, A is area of plate and d is distance between the plates.
• Hence the distance is inversely proportional to the capacitance and bringing the plates closer will mean reducing the distance and in effect increasing the capacitance of the system.
RRB JE EC CBT Test 1 - Question 98

What data type is ‘double’?

Detailed Solution for RRB JE EC CBT Test 1 - Question 98

The data type of a variable is an attribute that tells what kind of data that variable can have.

Data types can be divided into two major categories:
1. Primitive data type (predefined)
2. Non - primitive data type (user defined)

Primitive data type:
It is predefined types of data, which are supported by the programming language. For example, int, char, double, string etc. are all primitive data types.

Non - primitive data type:
They are not defined by the programming language but are instead created by the programmer.
For example, objects, interfaces etc.

RRB JE EC CBT Test 1 - Question 99

Which of the following is NOT true with respect to Kirchhoff's first law?

Detailed Solution for RRB JE EC CBT Test 1 - Question 99
• Kirchhoff's second law is called loop law.
• According to Kirchhoff's first law, the sum of currents which are meeting at a point (junction) in a circuit is always 0. It is therefore also called junction law.
• According to the sign convention adopted for this law, the current flowing towards the junction is taken as positive and the current leaving the junction is taken as negative.
• These two laws were given by Kirchhoff in 1842.
RRB JE EC CBT Test 1 - Question 100

A 555 timer IC is used as a monostable multivibrator. If a 10 μF timing capacitor is used, the value of capacitor required to produce a 500 m-sec voltage high pulse is _______ kΩ

Detailed Solution for RRB JE EC CBT Test 1 - Question 100

The time for which output remains high in the monostable multivibrator circuit is:
τ = 1.1 RC

RRB JE EC CBT Test 1 - Question 101

Identify the incorrect statement/option: The psychological effect of noise pollution is

Detailed Solution for RRB JE EC CBT Test 1 - Question 101

Noise pollution may cause or contribute to the following adverse effects:

• anxiety, stress, nervousness, nausea, headache,
• emotional instability,
• argumentativeness,
• increase in social conflicts
• depression and fatigue
• Insomnia as a result of lack of undisturbed and refreshing sleep
RRB JE EC CBT Test 1 - Question 102

The time constant of the network shown is:

Detailed Solution for RRB JE EC CBT Test 1 - Question 102

Remove the inductor, Now Total resistance across the terminals is 1 + (1||1) = 3/2 Ω
The time constant is given by

RRB JE EC CBT Test 1 - Question 103

The relay which is most sensitive to power swings is

Detailed Solution for RRB JE EC CBT Test 1 - Question 103

Power swings refer to oscillation in active and reactive power flows on a transmission line consequent to a large disturbance like a fault. The oscillation in the apparent power and bus voltages is seen by the relay as an impedance swing on the R-X plane. If the impedance trajectory enters a relay zone and if stays there for sufficiently long time, then the relay will issue a trip decision on power swing.

RRB JE EC CBT Test 1 - Question 104

Which of the following alloy is used for making clocks and scientific instruments?

Detailed Solution for RRB JE EC CBT Test 1 - Question 104

Invar is an alloy composed of Iron, nickel, and Carbon where Iron is a major component with 63%, nickel with 36% and Carbon with 1%. Invar is an alloy used for making clocks and scientific instruments because of its property of negligible coefficient of expansion.

RRB JE EC CBT Test 1 - Question 105

Strait of Malacca separates which two land masses?

Detailed Solution for RRB JE EC CBT Test 1 - Question 105
• Strait of Malacca is a narrow stretch of water which separates the Malay Peninsula and Indonesian Island of Sumatra.
• It was named after the Malacca Sultanate which ruled between 1400 and 1511 over a group of islands.
RRB JE EC CBT Test 1 - Question 106

Internet Protocol was invented by

Detailed Solution for RRB JE EC CBT Test 1 - Question 106

IP is a set of rules governing the format of data sent over the Internet or other network. Its routing function enables internet working, and essentially establishes the Internet. It was invented in 1974 by Vint Cerf.

RRB JE EC CBT Test 1 - Question 107

Detailed Solution for RRB JE EC CBT Test 1 - Question 107
• A 3-bit full adder is a combinational circuit
• Output depends only on the present input bits
• Hence there is no memory in a 3-bit full adder
RRB JE EC CBT Test 1 - Question 108

For Ku band of satellite communication, the uplink and downlink frequencies (in GHz) used for communication are:

Detailed Solution for RRB JE EC CBT Test 1 - Question 108

Various frequency bands and their uplink and downlink frequencies used in satellite communication are shown in the table below

RRB JE EC CBT Test 1 - Question 109

The property of good anode in a battery is?
i. It should be a good reducing agent
ii. It should be a good oxidizing agent
iii. It should have a negative redox potential
iv. It should have a positive redox potential

The correct statements are

Detailed Solution for RRB JE EC CBT Test 1 - Question 109

Anode:

• An anode is an electrode where the oxidation reaction occurs
• An anode is reducing agent
• Anode should have high conductivity
• Anodes have negative redox potentials

Cathode:

• A cathode is an electrode where reduction occurs
• A cathode is an oxidizing agent
• Cathodes have positive redox potentials
RRB JE EC CBT Test 1 - Question 110

Auto reclosing is used in case of

Detailed Solution for RRB JE EC CBT Test 1 - Question 110
• Air blast circuit breakers employ a high-pressure air blast as an arc quenching medium. Under normal condition, the contacts are closed
• When a fault occurs contacts are opened and an arc is struck between them
• Auto-reclosing is used in case of air blast C.B.
• Reclose is a circuit breaker along with protection system for overhead power lines & designed to reclose on to a fault
• It detects a fault and opens for a pre-programmed time, before closing again automatically. This cycle can be repeated 4 times
RRB JE EC CBT Test 1 - Question 111

Slew rate in an op-amp limits:

Detailed Solution for RRB JE EC CBT Test 1 - Question 111

The slew rate of the op-amp is given by:

A maximum value of change of output voltage is AViω
If the slew rate is 1V/sec
Then AViω ≤ 1
The maximum value of the rate of change of output is a function of input frequency ω
Hence slew rate limits the maximum frequency of operation in an op-amp

RRB JE EC CBT Test 1 - Question 112

The optical phenomenon that is primarily responsible for the observation of rainbow on a rainy day is ________.

Detailed Solution for RRB JE EC CBT Test 1 - Question 112

RRB JE EC CBT Test 1 - Question 113

A J-K flip flop can be made from and S-R flip flop by using two additional

Detailed Solution for RRB JE EC CBT Test 1 - Question 113

To realize a J-K flip flop an S-R flip flop, we should have-

So, we have to use two additional AND gate.

RRB JE EC CBT Test 1 - Question 114

In FORTAN and PASCAL Programming language they allocate memory space for arrays _________

Detailed Solution for RRB JE EC CBT Test 1 - Question 114

FORTRAN and PASCAL both are procedural/imperative compiled third generation languages.

They allocate memory space for arrays during program compilation so the size of the array is fixed.

RRB JE EC CBT Test 1 - Question 115

Which of the following techniques is non-linear modulation techniques?

Detailed Solution for RRB JE EC CBT Test 1 - Question 115

The linear modulator is the one that satisfies the principle of superposition:

The linear modulator techniques are:

• DSC SC
• Conventional AM
• SSB
• VSB

Non-linear modulation techniques are:

• FM
• PM
RRB JE EC CBT Test 1 - Question 116

In Schmitt trigger, the hysteresis width is given by:

Detailed Solution for RRB JE EC CBT Test 1 - Question 116

The hysteresis diagram of the Schmitt Trigger is shown in the figure

From the Figure:
Hysteresis width is given by the difference of upper threshold point and the lower threshold point
UTP - LTP = βVsat – (- βVsat) = 2βVsat

RRB JE EC CBT Test 1 - Question 117

For the 8085 assembly language program given below, the content of the accumulator and carry after execution of the program is__ _.

Detailed Solution for RRB JE EC CBT Test 1 - Question 117

Initially A = 00110101, Carry = 1
After RLC A = 01101010, Carry = 0
After RLC A = 11010100, Carry = 0
ADD B → Add A = D4H and B = 35 H
Now A = (D4 + 35)H = 09 H, Carry = 1

RRB JE EC CBT Test 1 - Question 118

Fundamental rights in the Indian constitution has been taken from which country's constitution?

Detailed Solution for RRB JE EC CBT Test 1 - Question 118
• Fundamental rights in the Indian constitution has been taken from the US constitution.
• The other features that have been borrowed from the US Constitution are:

1. Impeachment of the president
2. Functions of president and vice-president
3. Removal of Supreme Court and High court judges
4. Judicial review
5. Independence of judiciary
6. The preamble of the constitution

RRB JE EC CBT Test 1 - Question 119

A double beam oscilloscope has

Detailed Solution for RRB JE EC CBT Test 1 - Question 119
• The dual beam oscilloscope has two separate electron beams, and therefore two completely separate vertical channels
• The two channels may have a common time base system or they have an independent time base system
• An independent time base allows different sweeps rates for the two channels but increase the size and weight of the oscilloscope
RRB JE EC CBT Test 1 - Question 120

Which of the following is the information retrieval service?

Detailed Solution for RRB JE EC CBT Test 1 - Question 120
• The internet is a globally connected network system that transmits data via various types of media; Sometimes it is referred to as a ‘network of networks’
• The World Wide Web, or simply web, is a way of accessing information over the medium of the internet
• A web browser is a software application for accessing information on the World Wide Web
RRB JE EC CBT Test 1 - Question 121

Which of the following sinusoidal oscillators are L-C oscillators
I. Wien oscillator
II. Colpitts oscillators
III. Hartly oscillators
IV. Phase Shift oscillators

Detailed Solution for RRB JE EC CBT Test 1 - Question 121

Different types of oscillators are:

1. LC Oscillators:

• Colpitts Oscillator
• Clapp's Oscillator
• Hartley Oscillator

2. RC Oscillators

• Wein Bridge Oscillator
• RC Phase shift oscillator
RRB JE EC CBT Test 1 - Question 122

Clamp-on type and split-core type CTs are used because

Detailed Solution for RRB JE EC CBT Test 1 - Question 122
• Clamp-on type and split-core type CTs measure the current in a heavy-current conductor or bus-bar without breaking the current circuit
• The split core of the CT along with the secondary winding is simply clamped around the main conductor, which acts as the primary winding of the CT
• When used with range selectable shunts and a calibrated ammeter, clam on type CTs can be very conveniently used for direct and quick measurement of current
RRB JE EC CBT Test 1 - Question 123

The disease which is not caused by water pollution is

Detailed Solution for RRB JE EC CBT Test 1 - Question 123

Asthma is a condition in which a person's airways become inflamed, narrow and swell and produce extra mucus, which makes it difficult to breathe. It is caused due to air pollution.

RRB JE EC CBT Test 1 - Question 124

In the following figure, the equivalent resistance at terminals A and B will be

Detailed Solution for RRB JE EC CBT Test 1 - Question 124

In the given circuit, 50 Ω, 75 Ω and 50 Ω resistors are connected in parallel.
The equivalent resistance of this parallel combination is,

This parallel combination is in series is with 100 Ω.
Equivalent resistance is, Req = 18.75 + 100 = 118.75 Ω

RRB JE EC CBT Test 1 - Question 125

Systematic errors are

Detailed Solution for RRB JE EC CBT Test 1 - Question 125

Systematic errors:

• Systematic errors occur as a result of a flaw in the experiment design or apparatus
• Systematic errors cause the measured values to be consistently higher or lower than the actual value
• They cannot be reduced by conducting repeat trials

Systematic errors are divided into three part:

• Instrumental error
• Observational error
• Environmental error
RRB JE EC CBT Test 1 - Question 126

Who has assumed the charge as Vice Chief of the Naval Staff on 30 Jan 2019?

Detailed Solution for RRB JE EC CBT Test 1 - Question 126
• Vice Admiral G Ashok Kumar, AVSM, VSM assumed charge as Vice Chief of the Naval Staff on 30 Jan 2019.
• Kumar has held various Staff and Command assignments during his distinguished naval career spread over more than three decades.
• He is an alumnus of National Defence Academy, Khadakvasla, Pune and was commissioned into the Executive Branch of the Indian Navy on 01 Jul 1982.
RRB JE EC CBT Test 1 - Question 127

The potential of neutral is

Detailed Solution for RRB JE EC CBT Test 1 - Question 127

The potential of neutral is low and potential of earth is zero.

RRB JE EC CBT Test 1 - Question 128

Control bus in a microprocessor are:

Detailed Solution for RRB JE EC CBT Test 1 - Question 128

Control Bus is a group of conducting wires, which is used to generate timing and control signals to control the associated peripherals, the microprocessor uses control bus to process data.

Some control signals are:

• Memory write
• I/O Write
• Opcode fetch
RRB JE EC CBT Test 1 - Question 129

The shape of Indifference curve indicates ________.

Detailed Solution for RRB JE EC CBT Test 1 - Question 129

An indifference curve is a graph showing combination of two goods that give the consumer equal satisfaction and utility. Each point on an indifference curve indicates that a consumer is indifferent between the two and all points give him the same utility.

RRB JE EC CBT Test 1 - Question 130

Where was the Vaikom Satyagraha (1924-25) started?

Detailed Solution for RRB JE EC CBT Test 1 - Question 130

Vaikom Satyagraha was a Satyagraha in Travancore, Kerala against untouchability in Hindu society.

• The movement was cantered at the Shiva temple at Vaikom, near Kottayam.
• The Satyagraha aimed at securing freedom to all sections of society through the public roads leading to the Sri Mahadeva Temple at Vaikom.

Hence, 1 is the correct answer.

RRB JE EC CBT Test 1 - Question 131

The A scope of a radar displays:

Detailed Solution for RRB JE EC CBT Test 1 - Question 131
• A-Scope:

A-display, shows only the range, not the direction, to targets.

• B-Scope:

provides a 2-D "top-down" representation of space, with the vertical axis typically representing the range and the horizontal axis azimuth (angle)

• C-Scope:

A C-scope displays a "bullseye" view of azimuth vs. elevation

RRB JE EC CBT Test 1 - Question 132

Which earthing is better

Detailed Solution for RRB JE EC CBT Test 1 - Question 132

The pipe earthing is better than plate earthing, because it can earth more leakage current, and the possibility of braking in the earth wire is minimum.

RRB JE EC CBT Test 1 - Question 133

What is the SI unit of angular frequency?

Detailed Solution for RRB JE EC CBT Test 1 - Question 133
• The SI unit of angular frequency is rad/sec.
• It refers to the angular displacement of an object per unit time and is given by:

ω = ν × 2π
where, νν is the frequency.

RRB JE EC CBT Test 1 - Question 134

With an increase in temperature, the Fermi level in an intrinsic semiconductor

Detailed Solution for RRB JE EC CBT Test 1 - Question 134

The Fermi level of an intrinsic semiconductor is unchanged and remains at the center of the forbidden band gap. As temperature increases, both electron and holes are produced in equal number keeping the semiconductor intrinsic and Fermi level stays at the center.

RRB JE EC CBT Test 1 - Question 135

Which one is an input device of the computer?

Detailed Solution for RRB JE EC CBT Test 1 - Question 135

Components of Computer
Input Devices

Input devices are used to enter data or instructions into a computer.

• Keyboard
• Mouse
• Digital camera
• Scanner
• Mic
• Joystick

Output Devices:
Output unit receives the information from the processing unit and provides the result in a human-readable form.

• A visual display unit (Monitor, Screen)
• Printer/Plotter
• Multimedia projector
• Speaker

Storage Devices
Storage devices are the computer hardware used to remember/store data.

• Floppy disks
• Hard disks
• CD/DVD
RRB JE EC CBT Test 1 - Question 136

A series regulator using a transistor is shown below, the output voltage Vo is:

Detailed Solution for RRB JE EC CBT Test 1 - Question 136

Apply KVL from output terminal V0 to base terminal of Zener diode:
V0 + VBE – VZ = 0
V0 = VZ - VBE

RRB JE EC CBT Test 1 - Question 137

The sensitivity of microphone is measured in:

Detailed Solution for RRB JE EC CBT Test 1 - Question 137
• Sensitivity is the amount of voltage developed or generated by the microphone for an applied sound pressure at a test frequency of 1000 Hz
• It is generally specified as mV/Microbar
• One‐microbar sound pressure is equal to 1 dyne/cm2
• It is also specified as mV/Pa where Pa is Pascal, which is equal to 10 microbars
RRB JE EC CBT Test 1 - Question 138

The chemical formula of Hematite is ________.

Detailed Solution for RRB JE EC CBT Test 1 - Question 138
• The chemical formula of Hematite is Fe2O3called as ferric oxide. It is a reddish black mineral and an ore of Iron.
• FeO(OH).nH2is also an ore of Iron and is the chemical formula of Limonite.
• FeS2 is the chemical formula of Pyrite.
RRB JE EC CBT Test 1 - Question 139

For the op-amp circuit shown, the slope of the graph between Vout on the y-axis and Vin on the x-axis is ___

Detailed Solution for RRB JE EC CBT Test 1 - Question 139

The gain of the Non-inverting op-amp is given by the relation

RRB JE EC CBT Test 1 - Question 140

Norton’s theorem when applied to DC circuit results in:

Detailed Solution for RRB JE EC CBT Test 1 - Question 140

Norton’s theorem is applied to the DC circuits, it will result in a current source with resistance in parallel.
Thevenin’s theorem is applied to the DC circuits, it will result in a voltage source with a resistance in series.

RRB JE EC CBT Test 1 - Question 141

Which of the following is/are effects of ozone depletion?

Detailed Solution for RRB JE EC CBT Test 1 - Question 141

Effects of ozone depletion

• It produces a greenhouse effect and also changes the climate
• It results in low production of crops
• It causes damage to the organs of living things
• Ultraviolet rays harm the plants
• It causes to spread the skin cancer disease
• It raises the possibilities of acid rains in urban areas
• It increases the temperature of the environment
• It affects the mental health of man
• It increases the temperature of the atmosphere which has a bad effect on the vegetation
• The UV rays reaching the earth are harmful to the pregnant women and the infant children also
RRB JE EC CBT Test 1 - Question 142

EPROM stands for

Detailed Solution for RRB JE EC CBT Test 1 - Question 142

RRB JE EC CBT Test 1 - Question 143

The process of producing chemical decomposition of a compound by passing electricity through the compound is called

Detailed Solution for RRB JE EC CBT Test 1 - Question 143

The process of producing chemical decomposition of a compound by passing electricity through the compound is called electrolysis.

RRB JE EC CBT Test 1 - Question 144

Which of the following statement is correct?

Detailed Solution for RRB JE EC CBT Test 1 - Question 144
• In Diamagnetic materials, a very weak form of magnetism that is non-permanent exists only while the external field is being applied
• The relative permeability is small and less than unity
• In paramagnetic materials, each atom possesses a permanent dipole moment by virtue of incomplete cancellation of electron spin and orbital magnetic moments
• At the macroscopic level, these magnetic moments cancel out each other and there is no net magnetism in the absence of an electric field
RRB JE EC CBT Test 1 - Question 145

The internal quantum efficiency of LEDs decreases _______ with_______ temperature.

Detailed Solution for RRB JE EC CBT Test 1 - Question 145
• The efficiency of LEDs will be determined by the radiate recombination rate
• Temperature influence the output power of an LED through its effects on the internal quantum efficiency of the device, where decrease exponentially with increasing temperature
• The internal quantum efficiency of LEDs decreasing exponentially with increasing temperature
RRB JE EC CBT Test 1 - Question 146

Which is an 8-bit microprocessor?

Detailed Solution for RRB JE EC CBT Test 1 - Question 146

In 1979, Intel introduced the 8088, the 8-bit microprocessor. (external 8-bit data bus) instead of a 16-bit bus of 8086.

8085 is called 8-bit microprocessor because the accumulator is 8 bits in size. This means that the primary data size is 8 bits.

8086 is a 16-bit microprocessor.

RRB JE EC CBT Test 1 - Question 147

A voltage of 200 V at 5 Hz is applied to an electrodynamometer type of instrument which is spring controlled. The indication of the instruments is

Detailed Solution for RRB JE EC CBT Test 1 - Question 147

A voltage of 200 V at 5 Hz is applied to an electrodynamometer type of instrument which is spring controlled. The indication on the instruments is the instrument follows the variations in voltage and does not give a steady response.

RRB JE EC CBT Test 1 - Question 148

An Up-counter with 10 flip-flops is initially set zeros in all the flip flops; after 1050 clock pulses the binary number in the counter is

Detailed Solution for RRB JE EC CBT Test 1 - Question 148
• Up to 1023 clock pulses the binary number in counter goes from 000000000 to 1111111111
• Then on 1024 resets to all Flip flop at 0
• At 1050 clock pulse the number in the counter is binary of 26 i.e 0000011010
RRB JE EC CBT Test 1 - Question 149

The r.m.s. value of a sine wave is 100 A. Its peak value is

Detailed Solution for RRB JE EC CBT Test 1 - Question 149

We have rms value given by,

where, ​Vm is a peak value.
Thus, we have
Hence,

RRB JE EC CBT Test 1 - Question 150

When is the World Earth Day celebrated?

Detailed Solution for RRB JE EC CBT Test 1 - Question 150
• The World Earth Day is celebrated on 22nd April annually to support the environmental protection.
• It was first celebrated in 1970, by United State Senator Gaylord Nelson.

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