BEL Trainee Engineer Electrical Mock Test - 6 - Electrical Engineering (EE) MCQ

Concept:

Voltage regulation of the transmission line is defined as the ratio of the difference between sending and receiving end voltage to receiving end voltage of a transmission line between conditions of no-load and full load.

It can be expressed in percentage as

Sending end voltage for the transmission line is given as,

V_S =AV_r + BI_r

Under no-load condition, Ir = 0

Calculation:

Voltage at sending-end,

V_s = AV_R + BI_R

At no-load, I_R = 0

From the given data,

V_RF = 220 kV

From the above concept,

Most of the industrial loads can be classified into the following 4 general categories:

• Constant torque type load
• Torque proportional to speed (generator type load)
• Torque proportional to the square of speed (fan type load)
• Torque inversely proportional to speed (constant power type load)

Constant torque type load:

• Separately excited dc generators connected to a constant resistance load, eddy current brakes have speed-torque characteristics given by T = KW

Torque proportional to the square of speed (Fan type load):

• The torque speed curve of a load is a plot showing its torque requirement on the y-axis versus the speed on the x-axis.
• It’s the torque requirement of the load from zero speed to full speed.
• It’s application/load specific and varies with different load types.
• Load like centrifugal pumps and fan follows quadratic speed torque curve, where torque varies square times the speed.

Torque inversely proportional to speed:

• Load power remains constant in this type of load
• Lather, boring machine, milling machines, steel mill coiler, and electric traction load have this type of torque-speed characteristic.

Metal Drawing load:

• Metal drawing is a manufacturing process to do bulk deformation in metal work is worked upon to reduce its cross-sectional area.
• The bulk deformation signifies the massive changes in shape and a significant amount of deformation has been done.

To obtain high switching speed in BJT-based logic circuits, transistors are operated in the saturation region.

In the active region, the transistor works as a linear element because the Q point is chosen such that the performance is linear, and we don't see any harmonics in the output. Hence R is true.

A is but R is true

Important points:

Applications of different motors are given below.

• DC Series motor: It has a very high starting torque. Hence it is used for heavy-duty applications such as electric railways, mine hoists, continuous conveyors cranes, metallurgical works etc.
  
• DC Shunt motor: This is almost constant speed motor and its torque varies nearly as the current. Hence, it is used for driving constant speed line shafts, lathes, constant speed head centrifugal pumps, fans wood working machines, reciprocating pumps, laundry washing machines, milling machines, grinders, small printing presses, paper making machines, metal cutting machines etc.
  
• Squirrel Cage Induction Motors are suitable for applications where the drive requires constant speed, low starting torque, and no speed control drives.
  
• DC Cumulative compound motor: It has high starting torque and has varying speed within limits i.e. it has self-adjustable speed with changing load. Hence, it is used for driving compressors, pressure blowers, door lifts, circular saws, passenger elevators, freight elevators etc.
  
• DC Differentially compound motor: It has low starting torque and has a constant speed, but the dangerously high speed at no load under the circumstances it is seldom used.

Concept:

Equation of current is I = Im sin ωt

I_m = Maximum current

ω = Angular frequency = 2πf

f = Frequency

Calculation:

Given, I = 100 A

f = 50 Hz

100 = 200 sin 2 × π × 50 × t

100 × π × t = 30° = π/6

t = 1/600 s

t = 1.666 ms

Concept:

A number system includes the number of independent digits used in the number system (the base), the place values of the different digits constituting the number, and the maximum numbers that can be written with the given number of digits.

Octal numbers: These numbers use digits from 0 to 7, total of 8 digits, and hence they are called octal number system. Octal numbers have base 8.

Hexadecimal numbers: The numbers which have base 16. It uses 16 different digits to represent the numbers. It is denoted as h16, where h is a hexadecimal number. It may be a combination of alphabets and numbers. Thus, it includes numbers from 0 to 9 and alphabets A to F.

Calculation:

Hexadecimal to Octal Conversion:

Given, B3416 is a hexadecimal number.

B → 1011, 3 → 0011, 4 → 0100

1011 0011 0100

Now group them from right to left, each having 3 digits.

101, 100, 110, 100

101 → 5, 100 → 4, 110 → 6, 100 → 4

Hence, B3416 = 54648

Key Points

There is grouping of 3 from right to left since octal has base of 8, and 8 = 2³, i.e. power 3.

Concept:

For conversion of octal to Hexadecimal, first, convert the given octal number to binary and then binary number to hexadecimal.

Calculation:

Given octal no = 7 3 4

Convert each octal digit to binary: 111 011 100

Group of 4 bits is: 0001 1101 1100

Convert 4 bits group to hexadecimal: 1 D C

Concept:

Laplace transform is defined by:

Where,

f(t) is the function varying with time t

F(s) is the Laplace transform of f(t)

Laplace Inverse transform is defined by:

L-1 {F(s)} = f(t)

Inverse Laplace transform is derived as shown

The above equation indicates that

H ( σ + jω ) is a Fourier transform of

Hence the inverse Fourier transform of H (σ + jω) must be

i.e,

A change of variable is performed by letting, s = σ + jω,

which also yields dω = ds/j, s → (σ – j∞) as:

ω → - ∞ and s → (σ + j∞) as ω → ∞

Calculation:

By substituting in the above formula

Some important Laplace inverse transform are shown below:

Given: F(S) =

Therefore,

L-1 {F(s)} = f(t) = e-at sin (ω0t) u(t)

note: Some pairs of Laplace transforms are given below.

In squirrel cage induction motor, the rotor terminals are short-circuited. Hence we cannot add external resistance into the rotor circuit. So we cannot use is this method for starting.

Important Points:

The star-delta starter method of starting three-phase induction motors is very common and widely used among all the methods. In this method, the motor runs at delta-connected stator windings. It is used up to 20 hp.

The direct on line (DOL) starter method of an induction motor is simple and economical. In this method, the starter is connected directly to supply voltage. By this method, small motors up to 5 hp rating are started to avoid the supply voltage fluctuation.

The Autotransformer is used in both the type of the connections, i.e., either star connected or delta connected. The autotransformer is used to limit the starting current of the induction motor. This method is used for the high rating of squirrel cage induction motors. So, this method is most suitable for a above 25hp squirrel cage induction motor.

Concept:

To increase the range of a voltmeter, we need to the series resistance and it is given by

Where V is the required voltmeter range

Vm is the voltmeter range

Rm­ is the meter internal resistance

Calculation:

Given that,

Meter full scale current reading (Im) = 10 mA

Internal resistance (Rm) = 5 Ω

Voltmeter range (Vm­) = I m­ Rm = 10 × 10-3 × 5 = 0.05 V

Required voltmeter range (V) = 100 V

Concept:

Source transformation:

A current source in parallel with resistance can be represented as a voltage source in series with a resistance and vice versa.

The transformation is represented in the diagram given below.

Calculation:

By applying source transformation, the given circuit becomes

The current flowing through the 28 Ω resistor is,

Magnetic boundary conditions are the condition that must satisfy the boundary between two different media the fundamental boundary condition involving magnetic fields relate the tangential components of the magnetic field and the normal component of magnetic flux density on either side of the medium interface.

---(I)

Normal magnetic flux density:

Consider the interface two different materials with dissimilar permeability μ₁ and μ₂.

Here = tangential component on medium 1

= normal component on medium 1

= tangential component on medium

= Normal component on medium 2

Applying equation 1 on pull box and allowing Δh → 0

B_1n ΔS – B_2n ΔS = 0

(B = μH )

The normal component is continuous at the boundary.

The normal component is discontinuous at the boundary.

Tangential magnetic field:

Similarly, we can apply equation (2) to the enclosed both abcd shown in the figure below

As Δh → 0

H_1k – H_2k = k

(B = μH)

If the boundary is free of current than

It means the tangential component of is continuous while that of is discontinuous at the boundary surface.

The Program counter (PC):

• The program counter acts as a pointer to the next instruction to be executed and always contains the 16-bit address of the memory location of next instruction
• It is a 16 bit register as 8085 has 16 address lines
• The program counter is updated by the processor and points to the next instruction after the processor has fetched the complete instruction

Concept:

Time-domain specification (or) transient response parameters:

Delay time (td): It is the time taken by the response to change from 0 to 50% of its final or steady-state value.

Rise time (t­r): It is the time taken by the response to reach from 0% to 100% Generally 10% to 9% for overdamped and 5% to 95% for the critically damped system is defined.

Peak Time (tp): It is the time taken by the response to reach the maximum value.

Maximum (or) Peak overshoot (Mp): It is the maximum error at the O/P

If the magnitude of the input is doubled, then the steady-state value doubles, therefore Mp doubles, but % Mp, tr, tp remains constant.

Settling time (Ts): It is the time taken by the response to reach ± 2% tolerance band as shown in the fig above.

for a 5% tolerance band.

for 2% tolerance band

If ξ increases, rise time, peak time increases and peak overshoot decreases.

Calculation:

Characteristic equation: 1 + G(s)H(s) = 0

⇒ s² + 5s + 25 = 0

By comparing with the standard second order characteristic equation

ω_n = 5 rad/sec

ζ = 0.5

Damping ratio (ζ) = 0.5

Natural frequency (ωn) = 5 rad/sec

Settling time,

Peak time,

As we know that ,
Sublime is magnificent and great, base is anything low, ordinary, concise means short or compact, partial is not complete, and Insist is to make a request.
Therefore , required word is base . 

One word substitution is Stickler.

Disciplinarian: A person who believes in or practises firm discipline.

Stickler: A person who insists on a certain quality or type of behaviour.

Instantaneous: Occurring or done instantly.

Boaster: A very boastful and talkative person.

To activate the previous cell in a pre-selected range, you need to press a specific key. Let's go through each option to find the correct key.
A: The Alt key
- The Alt key is not used to activate the previous cell in a pre-selected range. It has other functionalities in Excel, such as accessing the ribbon menu.
B: The Tab key
- The Tab key is used to move to the next cell in a pre-selected range, not the previous cell. Pressing Tab will move the cursor to the cell on the right.
C: The Enter key
- The Enter key is used to move to the cell below the current cell in a pre-selected range. It does not activate the previous cell.
D: None of these
- This is the correct answer. None of the options provided (Alt key, Tab key, Enter key) are used to activate the previous cell in a pre-selected range.
In conclusion, the correct key to activate the previous cell in a pre-selected range is not listed among the options provided. Therefore, the answer is D: None of these.

My Computer is the feature that allows the user to view information about his computer hardware. Here is a detailed explanation:
- Start: The Start menu is the main gateway to access various features and applications on a computer, but it does not directly display information about the hardware.
- My Computer: This feature provides an overview of the computer's hardware components and storage devices. By clicking on "My Computer" or "This PC" (depending on the operating system), the user can see a list of drives, including the hard drive, optical drives, and any connected external storage devices. Right-clicking on any of these drives and selecting "Properties" will provide detailed information about the specific hardware.
- Control Panel: The Control Panel is a centralized location for managing various settings and features of the computer, but it does not directly display information about the hardware. However, within the Control Panel, there is a feature called "Device Manager" which provides detailed information about the hardware devices installed on the computer.
- All Programs: The "All Programs" feature is typically found in the Start menu and provides a list of installed applications on the computer. It does not directly display information about the hardware.
In conclusion, the correct answer is My Computer as it allows the user to view information about his computer hardware by providing an overview of drives and their properties.

The program that interacts with the inner part called kernel is known as Shell. Here is a detailed explanation:
Definition:
The Shell is a program that acts as an interface between the user and the operating system kernel. It allows users to interact with the operating system by executing commands and managing the system resources.
Key Points:
- The Shell provides a command-line interface (CLI) or a graphical user interface (GUI) for users to interact with the operating system.
- It interprets the commands entered by the user and executes them by communicating with the kernel.
- The Shell handles input/output redirection, command execution, file management, and other system operations.
- It provides features like command history, command completion, and scripting capabilities.
- Different operating systems have different types of shells, such as Bash (Bourne Again SHell) on Linux, PowerShell on Windows, and Terminal on macOS.
- The Shell also allows users to run scripts, which are sequences of commands stored in a file.
- It acts as an intermediary between the user and the kernel, translating user commands into instructions that the kernel can understand and execute.
Example:
Let's say a user wants to create a new directory. They can use the Shell by typing a command like "mkdir new_directory". The Shell will interpret this command and send a request to the kernel to create the directory. The kernel will then carry out the requested operation and inform the Shell of the result. The Shell will then display the appropriate message to the user.
Therefore, the correct answer is D: Shell.

A bootstrap is:

• Definition: A bootstrap is a small initialization program that starts up a computer system. It is responsible for loading and executing the operating system or other software components necessary for the system to function.


• Function: The bootstrap program resides in the computer's firmware or read-only memory (ROM) and is automatically executed when the system is powered on or restarted.


• Initialization: The bootstrap program initializes the hardware components of the computer, such as the processor, memory, and input/output devices.


• Bootloader: The bootstrap program then loads and executes a more complex bootloader, which further initializes the system and loads the operating system or other software from storage devices, such as hard drives or solid-state drives.


• Chain of Execution: The bootstrap process involves a chain of execution, where each component in the chain is responsible for loading and executing the next component until the operating system is fully loaded and running.


• Importance: The bootstrap program is crucial for the proper functioning of a computer system as it ensures that the necessary software is loaded and executed in the correct order.

In summary, a bootstrap is a small initialization program that starts up a computer system by loading and executing the necessary software components, such as the operating system. It plays a critical role in the boot process and ensures the proper functioning of the system.

A dot matrix printer is a type of printer that uses a matrix of small pins to create characters or images on paper. Let's analyze each statement to determine the correct answer:
i) Prints an entire line at a time: This statement is incorrect. A dot matrix printer prints one character at a time by striking an ink-soaked ribbon against the paper. It does not print an entire line at a time.
ii) Is a non-impact printer: This statement is incorrect. A dot matrix printer is an impact printer because it uses physical force to create the characters. The pins strike the ribbon, which transfers ink to the paper, resulting in the printed output.
iii) Allows multiple copies to be taken at a time: This statement is correct. Dot matrix printers have the ability to create multiple copies simultaneously. This is achieved by using carbon paper or carbonless paper, which allows the impact of the pins to transfer the image to multiple layers of paper.
iv) Prints one character at a time: This statement is correct. Dot matrix printers operate by individually striking pins against an ink-soaked ribbon to create characters. Each pin represents one dot, and the combination of dots forms the characters or images on the paper.
Based on the analysis above, the correct answer is C: iii and iv. A dot matrix printer allows multiple copies to be taken at a time and prints one character at a time.

Quickest way to select the entire worksheet:

• Step 1: Open the worksheet you want to select.


• Step 2: Locate the rectangle box on the upper left corner where column headings and row headings meet.


• Step 3: Click on the rectangle box.

Explanation:

The quickest way to select the entire worksheet is to click on the rectangle box on the upper left corner where column headings and row headings meet. This box is known as the "Select All" box and it allows you to select the entire worksheet in just one click.

This method is faster than other options because it saves you the time and effort of manually selecting each column or row. By clicking on the "Select All" box, you instantly select the entire worksheet including all columns, rows, and cells.

Using this method, you can quickly perform tasks such as formatting, copying, or deleting the entire worksheet without having to individually select each element. It is a time-saving technique that is particularly useful when working with large worksheets.

Therefore, the correct answer is Option D: Click on the rectangle box on the upper left corner where column headings and row headings meet.

The three basic boolean operators are: AND, OR, and NOT.

Hence, option D is correct.

As safe ans secure have same meaning in the same way protect and guard have same meaning.

As 'Dress' is worn on 'Body' similarly 'Bangles' are worn on 'Wrist'.