৪৯তম বিসিএস ⎯ তথ্য ও যোগাযোগ প্রযুক্তি [২৮১]

In machine learning, inductive reasoning is commonly used. It involves generalizing from specific instances or examples to form broader generalizations or patterns. This reasoning process is crucial in machine learning because algorithms learn from data and make predictions or inferences based on observed patterns in the training data.
Inductive Reasoning in Machine Learning:
•Inductive reasoning allows a system to draw conclusions about unseen data based on previously observed examples.
•In machine learning, inductive learning refers to the process of learning patterns or models from data and then generalizing these patterns to new, unseen instances.
•For example, a machine learning algorithm may learn to recognize images of cats by being trained on a dataset of labeled cat images and then generalize this understanding to recognize new, unlabeled images of cats.

Source: Artificial Intelligence: A Modern Approach by Stuart Russell and Peter Norvig

DBSCAN (Density-Based Spatial Clustering of Applications with Noise) is a popular clustering algorithm used in machine learning and data mining. It is particularly effective for datasets with noise and clusters of arbitrary shapes.
DBSCAN groups together points that are closely packed, marking as outliers points that are in low-density regions.
It uses two key parameters:
•Epsilon (ε): The maximum radius of the neighborhood around a point.
•MinPts: The minimum number of points required to form a dense region (a cluster).

Points that are not part of any cluster are considered noise.
Key Features of DBSCAN:
•It can find clusters of arbitrary shapes.
•It does not require the number of clusters to be specified in advance.
•It is robust to noise, which means it can handle datasets with outliers.

Source: Pattern Recognition and Machine Learning by Christopher M. Bishop

Convolutional Neural Networks (CNNs) are specialized deep learning models that are particularly effective for image recognition. CNNs use layers of convolutions to automatically detect patterns in image data, making them ideal for tasks like image classification and object detection.

Example:
A CNN might be used to classify whether an image contains a cat or a dog, by detecting edges, textures, and patterns that differentiate the two animals.

Source: Deep Learning by Ian Goodfellow, Yoshua Bengio, and Aaron Courville

Coulomb’s law specifically describes the electric force between two point charges. This force can either be attractive (for opposite charges) or repulsive (for like charges) and is central to the study of electrostatics.

Example:
Two charges, one positive and one negative, will attract each other with a force described by Coulomb's law.

Source: Introduction to Electrodynamics by David J. Griffiths

In a half-wave rectifier, the diode only conducts during the positive half-cycle of the AC input signal. During the negative half-cycle, the diode is reverse-biased and does not conduct.

Example:
In a half-wave rectifier with a sinusoidal AC input, the diode only conducts during the positive half of the AC cycle, clipping off the negative half, resulting in a pulsating DC output.

Source: Electric Circuits by James W. Nilsson and Susan A. Riedel

Black-box testing focuses on testing the external behavior of the software. The tester does not need to understand the internal code or logic. Instead, the goal is to ensure that the software works as expected by testing its functions and outputs against defined specifications.

Example:
In black-box testing of a login feature, the tester would verify that entering valid and invalid credentials produces the correct response (e.g., access granted or error message), without inspecting the underlying code.

Source: Software Engineering: A Practitioner's Approach by Roger S. Pressman

Cyclomatic Complexity is a software metric used to measure the complexity of a program by counting the number of independent paths through its source code. A higher cyclomatic complexity value indicates a more complex program that may be harder to test and maintain.

Example:
A method with multiple loops and conditionals will have a higher Cyclomatic Complexity compared to a simple method with a single conditional statement.

Source: Software Engineering: A Practitioner's Approach by Roger S. Pressman

Agile methodology emphasizes flexibility, iterative development, and continuous feedback. It breaks the project into smaller, manageable iterations (sprints), delivering a working software increment at the end of each sprint and allowing adjustments based on feedback.

Example:
A software development team using Scrum (a framework within Agile) might release a working feature every two weeks, gather feedback, and improve the product in subsequent sprints.

Source: Software Engineering: A Practitioner's Approach by Roger S. Pressman

The System Sequence Diagram (SSD) is used during the Elaboration phase to show the interactions between actors (users or other systems) and the system, focusing on the system's behavior and processing steps.

Example:
An SSD for an online banking system might show a user interacting with the system to initiate a transfer, with sequence steps like login, verify identity, and confirm the transfer.

Source: Software Engineering by Ian Sommerville

Use Case Modeling identifies the functional requirements of the system by describing the interactions between users (actors) and the system. It helps to understand the system's expected behavior from the user's perspective.

Example:
In an online shopping system, use cases may include placing an order, viewing product details, and checking out, showing how the user interacts with the system.

Source: Software Engineering by Ian Sommerville

Software Maintenance involves managing changes, fixing defects, adapting the system to new requirements, and ensuring its continued operation over time. This can be challenging due to evolving requirements, environmental changes, and bug fixes.

Example:
In a web application, maintenance might involve adding new features, upgrading to newer frameworks, or fixing security vulnerabilities over time.

Source: Software Engineering: A Practitioner's Approach by Roger S. Pressman

Monte Carlo simulation is a statistical technique used in project management to model the uncertainty and risk by simulating different possible outcomes based on variable inputs. It helps assess the probability of various project scenarios and estimate potential risks.

Example:
In a software development project, Monte Carlo simulation might estimate the likelihood of completing the project on time given varying estimates of task durations.

Source: Software Engineering by Ian Sommerville

User Interface (UI) Design focuses on creating an interface that is user-friendly, accessible, and enables users to efficiently interact with the software. A well-designed UI enhances the user experience by making the system easy to navigate and use.

Example:
A shopping cart UI should be simple and intuitive, allowing users to easily add or remove items, view their total cost, and proceed to checkout.

Source: Software Engineering: A Practitioner's Approach by Roger S. Pressman

The Spiral Model combines iterative development with systematic risk management. At each iteration, risk analysis is performed, and a risk-reduction plan is developed. This approach allows for continuous refinement of the system based on feedback and evolving requirements.

Example:
In a game development project, the first iteration might focus on creating a basic prototype and identifying risks (e.g., graphics rendering issues), which are addressed in subsequent iterations.

Source: Software Engineering: A Practitioner's Approach by Roger S. Pressman

White-box testing focuses on testing the internal workings of a software system. The tester has access to the internal code and tests the logic, flow, and structure of the code.
Path testing:
Path testing ensures that all possible execution paths in the program are tested. The goal is to cover every branch and path in the code to check if the logic works as expected.
This technique is directly related to analyzing the control flow of the program.

Source: Software Engineering: A Practitioner's Approach by Roger S. Pressman

The Verification model ensures that the system is being built correctly. Verification focuses on checking whether the system is being developed according to the specified requirements and design specifications. It answers the question, "Are we building the system right?"
Verification activities include Reviews, Inspections, Walkthroughs and Static analysis.
These activities ensure that the system meets the design and technical requirements and does not deviate from the expected specifications during development.

Source: Software Engineering: A Practitioner's Approach by Roger S. Pressman

The A Star Search Algorithm is a widely used search technique in both old and new AI approaches. It is an informed search algorithm that finds the shortest path from a start node to a goal node, using heuristics to optimize the search process.

Example:
In a robot navigation system, the A* algorithm might be used to find the shortest path from the robot’s starting point to the destination while avoiding obstacles.


Source: Artificial Intelligence: A Modern Approach by Stuart Russell and Peter Norvig

Knowledge engineering involves the process of capturing, organizing, and encoding knowledge from human experts into a format that can be used by AI systems, such as expert systems. This is critical for creating systems that can simulate human-like decision-making.

Example:
In a diagnostic system for agriculture, knowledge engineers work with agricultural experts to encode rules for diagnosing plant diseases based on symptoms.

Source: Artificial Intelligence: A Modern Approach by Stuart Russell and Peter Norvig

Markov Decision Processes (MDPs) are used to model decision-making in environments where outcomes are partly random and partly under the control of an agent. MDPs are crucial in reinforcement learning, where an agent takes actions to maximize rewards in a probabilistic environment.

Example:
In a robot navigation system, the robot needs to decide which actions to take (turn left, move forward) based on the current state, while considering the probabilities of different outcomes (e.g., obstacles).

Source: Artificial Intelligence: A Modern Approach by Stuart Russell and Peter Norvig

Apple Inc. was founded by Steve Jobs, Steve Wozniak, and Ronald Wayne in April 1976.
Steve Jobs: He was the visionary behind Apple, playing a key role in its product design and marketing strategy.
Steve Wozniak: He was the technical genius who designed and built the first Apple computer, the Apple I.
Ronald Wayne: He was a co-founder but sold his shares in the company early on and is often less recognized in Apple's history.

They founded Apple with the goal of creating and selling personal computers. The company's first product was the Apple I, which was followed by the Apple II, marking the beginning of Apple's rise to prominence in the tech industry.

Source: https://en.wikipedia.org/wiki/Apple_Inc.

An Expert System typically consists of a Knowledge Base (storing the rules and facts), an Inference Engine (to derive conclusions from the knowledge), and a User Interface (to interact with the user). It does not use a learning algorithm because it relies on manually encoded rules rather than learning from data.

Example:
In a legal expert system, the knowledge base may contain legal rules, and the inference engine may deduce legal advice based on user inputs, without learning from past cases.

Source: Artificial Intelligence: A Modern Approach by Stuart Russell and Peter Norvig

In supervised learning, the model is trained on a labeled dataset, meaning that for each input in the training data, the correct output (label) is provided. The algorithm learns the mapping from inputs to outputs and can then predict the output for new, unseen inputs.

Example:
In a spam detection system, the algorithm is trained with labeled emails (spam or not spam) and then classifies new emails as spam or not spam.

Source: Pattern Recognition and Machine Learning by Christopher M. Bishop

Naive Bayes Classifier is commonly used for sentiment analysis tasks in NLP. It is based on Bayes' theorem and works well for text classification problems, such as determining whether a review is positive or negative, by using the frequency of words as features.

Example:
A Naive Bayes classifier can be trained on labeled data, where positive reviews are labeled as "positive" and negative reviews as "negative", to predict the sentiment of new, unseen reviews.

Source: Pattern Recognition and Machine Learning by Christopher M. Bishop

In propositional logic, the common connectives (also called logical operators) are used to combine propositions. They include:
AND (∧): Conjunction, returns true if both propositions are true.
OR (∨): Disjunction, returns true if at least one of the propositions is true.
IF-AND-ONLY-IF (↔): Biconditional, returns true if both propositions have the same truth value (either both true or both false).

BETWEEN is not a logical connective in propositional logic. It's used in databases (e.g., in SQL) to check if a value falls within a specified range, but it has no role in formal logic.

Source: Pattern Recognition and Machine Learning by Christopher M. Bishop

DBSCAN (Density-Based Spatial Clustering of Applications with Noise) is particularly well-suited for datasets with outliers or noise because it can identify dense regions in the data and classify low-density points as noise. It does not require the number of clusters to be specified beforehand and can handle arbitrarily shaped clusters.

Example:
In geospatial data (e.g., mapping crime hotspots), DBSCAN can identify densely populated areas without being affected by isolated outlier points.

Source: Pattern Recognition and Machine Learning by Christopher M. Bishop

Blaise Pascal developed the Pascaline, the first mechanical calculator capable of performing basic arithmetic operations like addition and subtraction. It used a system of gears and dials to carry out calculations and is considered one of the earliest computing devices.

Example:
The Pascaline was used by Blaise Pascal to help his father with tax collection work. The device could add and subtract numbers by turning a series of wheels and could handle up to 8-digit numbers.

Source: Pattern Recognition and Machine Learning by Christopher M. Bishop

The ALU handles all mathematical calculations (addition, subtraction, multiplication, division) and logical operations (comparisons like AND, OR, NOT). It is a core part of the CPU.

Example:
When comparing two numbers to check which is greater, the ALU performs the comparison.

Source: Computer Networks by Andrew S. Tanenbaum

Input devices are used to provide data and control signals to a computer. A keyboard allows users to enter text and commands into the system.

Example:
Typing a command in the command prompt or entering text in a document involves using a keyboard as an input device.

Source: Computer Networks by Andrew S. Tanenbaum

Application software refers to programs designed to perform specific tasks for the user. Antivirus software is used to detect and remove malicious software from a computer, which is a specific task, unlike system software that helps run the computer.

Example:
Microsoft Word is another example of application software, designed for word processing tasks.

Source: Software Engineering by Ian Sommerville

To convert the decimal number 105 to its binary equivalent, we can use the division-by-2 method, where we repeatedly divide the number by 2 and record the remainders.
process:
105 ÷ 2 = 52, remainder = 1
52 ÷ 2 = 26, remainder = 0
26 ÷ 2 = 13, remainder = 0
13 ÷ 2 = 6, remainder = 1
6 ÷ 2 = 3, remainder = 0
3 ÷ 2 = 1, remainder = 1
1 ÷ 2 = 0, remainder = 1
Now, write the remainders from bottom to top then ​1101001

Therefore, the binary equivalent of the decimal number 105 is 1101001.

Source: Computer Organization and Architecture by William Stallings

We start by grouping the binary digits into 4-bit groups, starting from the right. If necessary, we pad the leftmost group with leading zeros.
Now we have, (Add a leading zero to make it a 4-bit group)
• The first group is 0001
• The second group is 0001
Now, we convert each 4-bit group into its hexadecimal equivalent,
0001 (binary) = 1 (hexadecimal)
In hexadecimal, 1 is again 1.
0001 (binary) = 1 (hexadecimal)
In hexadecimal, 1 is again 1.

Now, we combine the hexadecimal digits from each 4-bit group,
• The first group 0001 becomes 1.
• The second group 0001 becomes 1.
So, the hexadecimal equivalent of 10001 is 11

Source: Computer Organization and Architecture by William Stallings

The Identity Law in Boolean algebra states that any Boolean variable ANDed with 1 will result in the variable itself. Mathematically, A⋅1=A.

Example:
If A = 1, then A⋅1=1, and if A = 0, then A⋅1=0.

Source: Digital Design by M. Morris Mano

De Morgan's Second Law states that the complement of the OR operation of two variables is equal to the AND operation of their complements. In other words,
(A+B)′=A′⋅B′

Example:
For A = 1 and B = 0, the expression (A+B)′=(1+0)′=0 is the same as A′⋅B′=0⋅1=0.

Source: Digital Design by M. Morris Mano

A subtractor is a circuit used to perform binary subtraction. A half subtractor subtracts two bits and provides a difference and borrow bit. A full subtractor also includes a borrow-in bit from a previous operation.

Example:
In the case of A = 1 and B = 0, the difference will be 1, and the borrow will be 0.

Source: Digital Design and Computer Architecture by David Money Harris and Sarah L. Harris

In the TCP/IP model, the layers are ordered from top to bottom as follows:
i. Application Layer (provides user-level communication, e.g., HTTP, FTP)
ii. Transport Layer (handles end-to-end communication, e.g., TCP, UDP)
iii. Network Layer (handles routing of data, e.g., IP)
iv. Link Layer (responsible for the physical transmission of data, e.g., Ethernet)

Example:
When you access a webpage, the HTTP protocol operates at the Application Layer, TCP at the Transport Layer, IP at the Network Layer, and Ethernet at the Link Layer.

Source: Computer Networks (4th Ed.) by Andrew S. Tanenbaum

The Presentation Layer (Layer 6) is responsible for the formatting, encryption, and decryption of data to ensure it can be securely transmitted and understood between different systems.

Example:
SSL/TLS (Secure Socket Layer/Transport Layer Security) operates at the Presentation Layer to provide encryption for secure web communications.

Source: Computer Networking: A Top-Down Approach by James Kurose and Keith Ross

In HDLC, bit stuffing is used to ensure that the special flag sequence (01111110) does not appear within the data. Whenever five consecutive 1s are encountered in the data, a 0 is inserted to prevent this from happening.

Example:
If the data being sent is 1111101, bit stuffing adds a 0 after the fifth 1, resulting in 11111010.

Source: Data and Computer Communications by William Stallings

In HDLC, the flag sequence (01111110) is used to mark the start and end of a frame. It ensures that the receiver can correctly identify the boundaries of each frame, even in continuous data streams.

Example:
Each HDLC frame begins and ends with the flag sequence, which is typically 01111110, ensuring proper frame delimitation during transmission.

Source: Digital Design and Computer Architecture by David Money Harris and Sarah L. Harris

IEEE 802.11ac, also known as Wi-Fi 5, supports wireless data rates of up to 3.5 Gbps using multi-user MIMO (MU-MIMO) technology and operating in the 5 GHz frequency band. It offers faster speeds compared to the earlier 802.11n standard.

Example:
802.11ac is commonly used in modern wireless routers and offers high-speed wireless connections for demanding applications like HD video streaming and online gaming.

Source: Computer Networking: A Top-Down Approach by James Kurose and Keith Ross

In congestion control, the window size is adjusted to control the flow of packets. When congestion occurs, the sender reduces the number of packets it sends until the network can handle the load.

Example:
TCP uses window size adjustment (also known as flow control) to prevent congestion by limiting how many packets can be in transit at once.

Source: Computer Networks (4th Ed.) by Andrew S. Tanenbaum.

IPv6 (Internet Protocol version 6) is the successor to IPv4, and one of its key features is the use of 128-bit addresses, which allows for a vastly larger address space than the 32-bit addresses used in IPv4.

Example:
An example of an IPv6 address is 2001:0db8:85a3:0000:0000:8a2e:0370:7334.

Source: Computer Networks (4th Ed.) by Andrew S. Tanenbaum.

The ATM network layer is designed to support both voice and data transmission by using fixed-size packets called cells. It is connection-oriented and ensures high-speed, low-latency data transfer, making it ideal for multimedia applications.

Example:
ATM is used in telecommunications networks where high-speed and reliable transmission of voice, video, and data is required simultaneously.

Source: Data and Computer Communications by William Stallings

DES (Data Encryption Standard) is a symmetric key encryption algorithm used to encrypt data by applying the same key for both encryption and decryption. It is a block cipher that processes data in fixed-size blocks.

Example:
DES uses a 56-bit key to encrypt data in 64-bit blocks. The same key is used by the sender and receiver to secure communication.

Source: Computer Networks by Andrew S. Tanenbaum

To ensure email privacy, encryption is commonly used to protect the contents of email messages during transmission. This prevents unauthorized users from accessing or reading the emails.

Example:
S/MIME (Secure/Multipurpose Internet Mail Extensions) and PGP (Pretty Good Privacy) are two popular email encryption methods.

Source: Computer Networks by Andrew S. Tanenbaum

In C (and most structured programming languages), operators follow precedence rules. Multiplication (*) has higher precedence than addition (+), so the expression is evaluated as 5 + (2 * 3) which equals 5 + 6 = 11.

Example:
This is an example of an arithmetic expression where multiplication is performed before addition.

Source: C Programming Language by Brian W. Kernighan & Dennis M. Ritchie

The if-else statement is used to execute one block of code if the condition is true and another block if it is false. This is a fundamental control structure in structured programming.

Example:

if (x > 0) {
printf("Positive number");
} else {
printf("Non-positive number");
}


Source: Programming in C by Stephen G. Kochan

The scanf function is used for reading input. %d is the format specifier for reading integers. The & operator is used to provide the memory address where the integer should be stored.

Example:

int x;
scanf("%d", &x); // Reads an integer from the user and stores it in variable 'x'

Source: C Programming Language by Brian W. Kernighan & Dennis M. Ritchie

In C, errors are usually handled using the global variable errno which is set by standard library functions when an error occurs. The perror() function can then be used to print the error message related to errno.
Example:

In this case, if the file does not exist, perror() will print an appropriate error message.

Source: C Programming Language by Brian W. Kernighan & Dennis M. Ritchie

In C++, exceptions are handled using the try block to enclose code that may throw an exception, and the catch block to handle the exception. If an exception is thrown, control is transferred to the appropriate catch block.

Example:

In this example, the integer 10 is thrown and caught in the catch block.

Source: C++ Primer by Stanley B. Lippman

In the Relational Model, a relation is represented as a table, where each row is a tuple (or record) and each column represents an attribute. Relations are the foundation of relational databases.

Example:
A table named employees might be a relation where each row represents an individual employee and columns like employee ID, name, and salary represent attributes.

Source: Database Management Systems by Raghu Ramakrishnan

Relational Algebra is a procedural query language that works on relations (tables). The basic operations in relational algebra include:
• SELECT (σ) - filters rows based on a condition.
• PROJECT (π) - selects specific columns from a relation.
• JOIN - combines rows from two or more relations based on a related column.
• UNION, INTERSECTION, DIFFERENCE - set-based operations on relations.

The PROJECT operation (π) extracts specific columns from a relation, which is essential for simplifying the result.

Example:
π Name, Age (Employee)
This operation projects (selects) the columns Name and Age from the Employee relation.

Source: Database Management Systems by Raghu Ramakrishnan

The UNION operation combines the results of two queries, eliminating any duplicate tuples that may appear in the results. It is a set operation in relational algebra.

Example:
Employee ∪ Manager
This operation combines all employees and managers, removing any duplicates.

Source: Database Management Systems by Raghu Ramakrishnan

When a relation is decomposed into smaller relations, the lossless join property ensures that no data is lost during the decomposition. It means that when we join the smaller relations back together, we can recover the original relation without any loss of information.

Example:
Decomposing a table into two smaller relations, say R1 and R2, and ensuring that we can rejoin them to get back the original relation without losing any data, is a lossless decomposition.

Source: Database Management Systems by Raghu Ramakrishnan

Hashed file organization uses a hash function to compute the storage location of records based on a key value. This provides very fast access for exact match queries (where you know the exact value of the key). However, it is not ideal for range queries, as the records are not stored in any particular order.

Example:
In a hashed file organization, if we want to store employee records, the employee ID might be used as a key. The hash function would map each EmployeeID to a specific location on disk, allowing direct access to the record.

Source: Database Management Systems by Raghu Ramakrishnan

Indexing is a technique used to improve the performance of data retrieval. By creating an index on certain columns (like primary or foreign keys), the database system can quickly locate records without scanning the entire table.

Example:
An index on the EmployeeID column allows quick retrieval of employee records without having to search through every row in the Employees table.

Source: Database Management Systems by Raghu Ramakrishnan

The cost of a query execution plan is typically calculated based on the resources it is expected to consume, such as CPU usage, memory usage, and disk I/O operations. The optimizer chooses the plan with the least expected resource usage to improve query performance.

Example:
When a query involves a join, the optimizer might calculate the cost of each possible join order by estimating how much data needs to be read from disk, how many CPU cycles the operation will consume, and how much memory will be required to hold intermediate results.

Source: Database Management Systems by Raghu Ramakrishnan

Demand paging is an alternative to swapping in some operating systems. It loads only the necessary pages of a process into memory when needed, rather than swapping entire processes in and out of memory. This allows for more efficient memory use without the full overhead of swapping.

Example:
In demand paging, when a process tries to access a page that is not in memory, the operating system loads the page from disk into memory at that moment (this is known as a page fault).

Source: Operating System Concepts by Abraham Silberschatz, Peter Baer Galvin, and Greg Gagne

In the segmentation model, the process sees its memory as divided into different segments, each corresponding to a logical entity such as code, data, or stack. Each segment can vary in size depending on the structure and needs of the program.

Example:
A process may have:
• Code segment for program instructions.
• Data segment for global variables.
• Stack segment for function calls and local variables.
• Heap segment for dynamically allocated memory.

Source: Operating System Concepts by Abraham Silberschatz, Peter Baer Galvin, and Greg Gagne

Deadlock recovery can be achieved by terminating one or more processes involved in the deadlock. The operating system can choose to terminate the process that is blocking others or all processes involved in the deadlock. This frees up resources and breaks the deadlock.

Example:
If process P₁ and P₂ are deadlocked, the system might terminate P₁ to release its resources, allowing P₂ to continue.

Source: Operating System Concepts by Abraham Silberschatz, Peter Baer Galvin, and Greg Gagne

Preemption is a deadlock prevention technique in which the operating system forcibly takes resources away from a process to break the deadlock. If a process is holding resources and is waiting for others, the system can preempt one or more resources and assign them to another process.

Example:
In a deadlock situation, the operating system might preempt resources from process P₁ and allocate them to P₂, allowing P₂ to continue execution and avoid deadlock.

Source: Operating System Concepts by Abraham Silberschatz, Peter Baer Galvin, and Greg Gagne

File Allocation Table (FAT), New Technology File System (NTFS) and Hierarchical File System Plus (HFS+) are well-known file systems used by operating systems like Windows and macOS. Task File System (TFS) is not a commonly recognized file system standard.

Example:
FAT is used in older systems and flash drives, NTFS is a robust file system used in modern Windows operating systems, and HFS+ is used in macOS for efficient file storage.

Source: Operating System Concepts by Abraham Silberschatz, Peter Baer Galvin, and Greg Gagne

A conductor is a material that allows the flow of electric charge. Copper is one of the best conductors of electricity because it has a large number of free electrons (charge carriers) that are free to move in response to an electric field. Materials like wood, rubber, and plastic are insulators, which do not allow the free movement of charge.

Example:
Copper wires are commonly used in electrical circuits because of their high conductivity.

Source: Fundamentals of Physics by David Halliday, Robert Resnick, and Jearl Walker

By applying Gauss’s Law to a spherical surface enclosing a point charge q, the electric field at a distance r from the charge is given by:
E = kq/ r²

where,
k = 1/ 4πϵ₀ is Coulomb's constant
q is the point charge
r is the distance from the charge

Example:
The electric field due to a point charge q=1μC at a distance of 1 meter is calculated using the formula.

Source: Fundamentals of Physics by David Halliday, Robert Resnick, and Jearl Walker

The magnetic field around a long, straight current-carrying wire is given by Ampere's Law, which is represented by the formula:
B= μ₀I /2πr

Where:
B is the magnetic field (in tesla, T),
μ₀ is the permeability of free space, μ₀=4×10⁻⁷ T⋅m/A,
I is the current (in amperes, A),
r is the distance from the wire (in meters, m).

Given that,
I = 1 A (current),
r = 0.5 m (distance from the wire),
μ₀ = 4×10⁻⁷ T⋅m/A,

Now, substitute the given values into the formula:
B = { 4×10⁻⁷×1} / { 2π×0.5 }
= { 4×10^-7 } / {2×3.1416×0.5}
= 4×10^-7 / 3.1416
= 1.27×10^-7
∴ B = 1.27×10^-7 T (approximately)

The magnetic field at the point is approximately 1.27×10^-7 T.

Source: Fundamentals of Physics by David Halliday, Robert Resnick, and Jearl Walker

According to Faraday’s Law and Lenz's Law, the induced EMF will always oppose the change in magnetic flux. If the magnetic flux through a loop increases, the induced EMF will act to produce a current that generates a magnetic field opposing the increase in flux, thus resisting the change.

Example:
If the magnetic field through a loop is increasing, the induced EMF will generate a current that produces a magnetic field opposite to the direction of the increasing flux.

Source: Fundamentals of Physics by David Halliday, Robert Resnick, and Jearl Walker

Maxwell's equations are the set of four fundamental laws that govern electromagnetism. These include:
i. Gauss’s Law for Electricity: Describes the relationship between a static electric field and the electric charges that cause it.
ii. Gauss’s Law for Magnetism: States that there are no "magnetic charges" and that magnetic field lines are always closed loops.
iii. Ampere’s Law (with Maxwell's correction): Relates the magnetic field to the current and changing electric field.
iv. Faraday’s Law of Induction: Describes how a time-varying magnetic field induces an electric field.

Example:
The equations describe the behavior of electric and magnetic fields and their interactions with matter.

Source: Fundamentals of Physics by David Halliday, Robert Resnick, and Jearl Walker

Length contraction is a phenomenon where an object moving at a speed close to the speed of light will appear contracted in the direction of motion from the perspective of a stationary observer. The length contraction is described by the formula:

where L₀ is the proper length (length at rest), v is the velocity of the object, and c is the speed of light.

Example:
A spaceship moving at high speed relative to Earth will appear shorter to an observer on Earth, particularly in the direction of motion.

Source: Fundamentals of Physics by David Halliday, Robert Resnick, and Jearl Walker

To calculate the power dissipated in a resistor, we use Joule's Law:
P= I² × R
Where,
P is the power dissipated (in watts, W),
I is the current (in amperes, A),
R is the resistance (in ohms, Ω).

Given that,
Resistance, R = 50Ω,
Current, I = 30A.

Now, substitute the given values into the formula:
P = 30²×50
= 900 × 50
= 45000
∴ P = 45000 W

The power dissipated by the resistor is 45000 W.

Source: Fundamentals of Electric Circuits by Alexander and Sadiku

A resistor is an electrical component that limits the flow of electric current in a circuit. It converts electrical energy into heat according to Joule's Law:
P=I²R, where P is the power dissipated by the resistor.

Example:
A resistor in a circuit limits the current and dissipates energy in the form of heat, such as in a light bulb filament.

Source: Fundamentals of Electric Circuits by Alexander and Sadiku

Thevenin's Theorem states that any linear electrical network with voltage sources and resistances can be simplified into a single equivalent voltage source (Thevenin voltage V_th) in series with a single equivalent resistance (R_th).

Example:
For a complex circuit with multiple resistors and sources, we can replace it with a Thevenin equivalent consisting of V_th and R_th, which makes it easier to analyze the behavior of the circuit.

Source: Fundamentals of Electric Circuits by Alexander and Sadiku

Voltage (V) is given by:
V = W/Q
Where:
W = Work done (in Joules) = 100 J
Q = Charge (in Coulombs) = 25 C

Now, substitute the given values into the formula:
V = 100/25
= 4

∴ The answer is 4 V.

Voltage measures the energy per unit charge.
Here, 100 Joules of energy is used to move 25 Coulombs of charge, so each Coulomb “gains” 4 Joules of energy, meaning the potential difference is 4 volts.

Sources: Fundamentals of Physics by Halliday, Resnick & Walker

In the common base configuration, the current gain is less than 1 because the current that enters the base is much smaller than the current that exits the collector. However, this configuration provides a high voltage gain and is often used in high-frequency applications.

Example:
In a common base amplifier, the input current is applied to the base, and the output current from the collector is amplified, but the current gain is less than 1.

Source: Electric Circuits by James W. Nilsson and Susan A. Riedel

The stability factor S is significantly affected by temperature variations because β (current gain) of a transistor is temperature-dependent. As temperature increases, β typically increases, which can cause a shift in the operating point. This makes the circuit less stable.

Example:
For a transistor with a high stability factor, a small increase in temperature might cause a large variation in the current flowing through the transistor, leading to a change in the output signal.

Source: Electric Circuits by James W. Nilsson and Susan A. Riedel

The common-emitter amplifier typically provides high voltage gain, and it inverts the input signal. This means that the output voltage is negative relative to the input, resulting in a negative voltage gain. The voltage gain A_v is given by:
A_v=−g_mR_C
where,
g_m is the transconductance and R_C is the collector resistance.

Example:
For a transistor with a transconductance g_m=40mS and a collector resistance R_C=1kΩ, the voltage gain will be A_v=−40.

Source: Electric Circuits by James W. Nilsson and Susan A. Riedel

Proper biasing of a common emitter amplifier is critical to ensure that the transistor stays in the active region of operation, where it can amplify signals without distortion. If the transistor is biased into the cutoff or saturation region, it cannot function as an amplifier.
Example:
A DC biasing network is used to set the base voltage so that the transistor remains in the active region for both small-signal amplification and large-signal operation.

Source: Electric Circuits by James W. Nilsson and Susan A. Riedel

Internal data representation refers to how data is stored in memory using contiguous locations for structured formats (arrays, linked lists, etc.). In most programming environments, data structures like arrays and records are stored in memory with a fixed, predefined structure that allows for efficient access and manipulation of data.
Example:
An array of integers will be stored in contiguous memory locations, where each element can be accessed using its index.

Source: Structured Computer Organization by Andrew S. Tanenbaum

A Queue ADT is a real-world example, particularly in systems where tasks are performed in a first-in-first-out (FIFO) manner, such as in printer queues or task scheduling systems. The ADT specifies operations like enqueue and dequeue, but the underlying implementation can vary (e.g., using an array or linked list).

Example:
In a printer queue, print jobs are added to the queue and processed in the order they are received (FIFO). The queue is an ADT that controls the order of processing.

Source: Data Structures and Algorithm Analysis by Mark Allen Weiss

A Fibonacci Heap is a heap data structure consisting of a collection of heap-ordered trees. It is used for priority queue operations and has better amortized time complexity for many operations compared to traditional binary heaps.

Example:
A Fibonacci Heap is typically used in algorithms that require efficient decrease-key and merge operations, such as Dijkstra's shortest path algorithm.

Source: Structured Computer Organization by Andrew S. Tanenbaum

The N-Queens problem involves placing N queens on an N×N chessboard so that no two queens threaten each other. This problem is often solved using backtracking, where we try to place queens one by one and backtrack when a conflict arises.

Example:
For a 4-Queens problem, the algorithm will try to place a queen on the first row, move to the next row, and continue until all queens are placed or a conflict arises. If a conflict is found, it backtracks and tries a different arrangement.

Source: Structured Computer Organization by Andrew S. Tanenbaum

The Intel 80386 was a 32-bit microprocessor that introduced virtual memory and could address up to 4 GB of memory. This capability made it suitable for more complex computing tasks and operating systems like Windows to utilize more memory.

Example:
The 80386 was widely used in personal computers and workstations, supporting multitasking and advanced operating systems.

Source: Digital Logic and Computer Design by M. Morris Mano

The Intel 8086 is a 16-bit microprocessor with a 20-bit address bus, allowing it to address 1 MB of memory (since 2^20 = 1,048,576 bytes = 1 MB). This was a significant improvement over previous microprocessors like the 8085.

Example:
The Intel 8086 could access 1 MB of memory using segmented memory.

Source: Microprocessor Architecture, Programming, and Applications by Ramesh S. Gaonkar

The union of sets A and B, denoted A ∪ B, includes all elements that are in either A, B, or both. In this case, the union of A = {1, 2, 3, 4, 5, 6, 7, 8} and B = {1, 3, 5, 7} results in {1, 2, 3, 4, 5, 6, 7, 8}.

Solution:
A = {1, 2, 3, 4, 5, 6, 7, 8}
B = {1, 3, 5, 7}

A ∪ B = {1, 2, 3, 4, 5, 6, 7, 8}

Source: Discrete Mathematics and Its Applications by Kenneth H. Rosen

The Cartesian product of two sets A and B is the set of all ordered pairs where the first element is from A and the second element is from B.

Example:
If A = {x, y} and B = {a, b}, then A × B = {(x, a), (x, b), (y, a), (y, b)}.

Source: Discrete Mathematics and Its Applications by Kenneth H. Rosen

In computer systems, the method of retrieving or accessing data stored in memory is referred to as "reading". This process involves retrieving the stored data from a particular location in memory.
Reading means accessing the stored information from the computer's memory.
The term "Read" is the most commonly used term to describe this process.
"Read out" is not typically used in this context, although it can be understood in specific cases to mean extracting data.
"Read from" is a more verbose way of describing the action, but "Read" is the standard term.

Example:
In a computer program, when a value is requested from memory (e.g., variable x), the process is referred to as reading from memory:
x = memory_address  # Accessing the value stored at memory_address

Source: Computer Organization and Design: The Hardware/Software Interface by David A. Patterson and John L. Hennessy

The class of regular languages is closed under several operations, including union, intersection, and complement. This means that if L1 and L2 are regular languages, then L1 ∪ L2, L1 ∩ L2, and ¬L1 (complement of L1) are also regular languages.

Example:
If L1 = (a|b)* and L2 = (ab)*, their union L1 ∪ L2 is also regular, as is the intersection L1 ∩ L2 and the complement of L1.

Source: Introduction to the Theory of Computation by Michael Sipser

By the Handshaking Lemma, the sum of the degrees of all vertices in a graph is equal to twice the number of edges in the graph. This is because each edge contributes to the degree of two vertices.

Example:
In a graph with 5 edges, the sum of the degrees of all vertices would be 2×5=10.

Source: Introduction to Graph Theory by Douglas B. West.

In graph theory, the sum of the degrees of all vertices in a graph is twice the number of edges. This is known as the Handshaking Lemma, which states that:
∑degrees of all vertices=2×number of edges

Given that,
The sum of the degrees of all vertices = 20.
Let the number of edges in the graph be E. According to the Handshaking Lemma,
Sum of degrees of all vertices=2×number of edges
Now, substitute the given values into the formula,
20=2×E
or, E= 20/2
∴ E =10
The number of edges in the graph is 10

Example:
Consider a graph with 4 vertices and the following degrees:
Vertex 1: degree 3
Vertex 2: degree 3
Vertex 3: degree 2
Vertex 4: degree 2
The sum of the degrees is: 
3+3+2+2=10
So, using the Handshaking Lemma, the number of edges is:
10/2=5

Source: Introduction to Graph Theory by Douglas B. West

The format specifier %.3f rounds the floating-point number to 3 decimal places.
In this case, 3.56789 is rounded to 3.568.

Source: C Programming: A Modern Approach by K. N. King.

Path Coverage is a common technique used in White Box Testing. It involves testing all possible paths through a program to ensure that every potential execution path is covered. This is particularly important to identify issues like unreachable code or improper branching logic.

Example:
In a function with multiple decision points, path coverage will require testing every possible combination of true and false for each decision to ensure that every potential path is executed.

Source: Foundations of Software Engineering by Rajib Mall

For a signal to be represented by a Fourier Series, it must be periodic. The Fourier Series applies to periodic signals, where the pattern of the signal repeats over time. Non-periodic signals are typically analyzed using the Fourier Transform instead of the Fourier Series.
Example:
A sine wave of frequency 10 Hz is periodic and can be represented by a Fourier Series, with only one non-zero frequency component corresponding to 10 Hz.

Source: Introduction to Fourier Analysis by M.J. Roberts.

The quality of the reconstructed signal in PCM is determined by the number of quantization levels. The more levels available for quantization, the closer the quantized signal will be to the original analog signal. This results in higher signal fidelity. In PCM, the number of levels is directly related to the bit depth (the number of bits used to represent each sample).

Example:
If PCM uses 8 bits per sample, there are 2⁸ = 256 quantization levels. Increasing the bit depth improves the signal's quality by reducing quantization error.

Source: Understanding Digital Signal Processing by Richard G. Lyons.

Aliasing occurs when the sampling rate is too low to accurately represent the high-frequency components of a signal. According to the Nyquist theorem, the sampling rate should be at least twice the maximum frequency of the signal. If the sampling rate is lower than this, higher frequencies in the signal will be incorrectly represented, causing aliasing.

Example:
If a signal with a maximum frequency of 15 kHz is sampled at 20 kHz, the result will be aliasing. However, if the sampling rate is increased to 30 kHz or higher, aliasing can be avoided.

Source: Introduction to Digital Signal Processing by John H. Smith.

We apply the Inclusion-Exclusion Principle:
Total ways to select 2 cards from 52: 
         52! / 2! × (52-2)! 
      = 52! / (50!×2!)
      = 52 × 51/2 
      = 1326
Total ways to select 2 cards from 52 cards is 1326.

Source: Discrete Mathematics and Its Applications  (8th Ed.) by Kenneth H. Rosen

We apply the Inclusion-Exclusion Principle:
Numbers divisible by 4:
[100/3] = 25
Numbers divisible by 5: 
[100/5] = 20
Numbers divisible by both 4 and 5 (i.e., divisible by 20): 
[100/20] = 5

Now apply the Inclusion-Exclusion principle:
Divisible by 4 or 5=25+20−5=40.
The answer is 40.

Source: Discrete Mathematics and Its Applications  (8th Ed.) by Kenneth H. Rosen.

TDMA is commonly used in cellular mobile networks, where multiple users share the same frequency band by transmitting in different time slots. TDMA was used in earlier cellular technologies like GSM and is still relevant in some modern systems.

Example:
In GSM (Global System for Mobile Communications), users are assigned specific time slots within the same frequency band to transmit and receive data.

Source: Mobile Communications by Jochen Schiller

• 'Amend' এর বাংলা পরিভাষা - সংশোধন করা।

অন্যদিকে,
• 'Amenable' অর্থ - সংবেদনশীল; চালিত বা নিয়ন্ত্রিত হতে আগ্রহী এমন; বাধ্য; অনুগত।
• 'Amends' অর্থ - ক্ষতিপূরণ দান করা।
• 'Augmenting' অর্থ - পরিবর্ধন করা।

উৎস: বাংলা একাডেমি, প্রশাসনিক পরিভাষা এবং অভিগম্য অভিধান।

• 'বাতাস' শব্দের সমার্থক শব্দ:
বায়ু, হাওয়া, পবন, সমীর, সমীরণ, অনিল, মরুৎ, প্রভঞ্জন।

অন্যদিকে,
• 'পানি' শব্দের সমার্থক শব্দ: অম্বু, জল, নীর, সলিল, অপ, উদক, তোয়, জীবন ইত্যাদি।
• 'তুষার' শব্দের সমার্থক শব্দ: বরফ; হিমানী; নীহার।
• 'মেঘ' শব্দের সমার্থক শব্দ: জলধর; জীমূত; বারিদ; নীরদ; পায়োদ; ঘন।

উৎস: বাংলা একাডেমি, আধুনিক বাংলা অভিধান; অভিগম্য অভিধান এবং ভাষা-শিক্ষা, ড. হায়াৎ মামুদ।

• ভারতচন্দ্র রায়:
- কবি রায়গুণাকর ভারতচন্দ্র আঠার শতকের শ্রেষ্ঠ কবি। তিনি মধ্যযুগের বাংলা সাহিত্যের অন্যতম শ্রেষ্ঠ কবি হিসেবেও মর্যাদার অধিকারী। মঙ্গলকাব্য ধারার শেষ কবি ভারতচন্দ্র বিদ্যাসুন্দর কাহিনিরও শ্রেষ্ঠ কবি রূপে পরিগণিত।

- কবি ভারতচন্দ্রের প্রতিভার শ্রেষ্ঠ নিদর্শন 'অন্নদামঙ্গল' কাব্য। 'কালিকামঙ্গল' ও 'বিদ্যাসুন্দর' এই কাব্যের অংশমাত্র।
- ভারতচন্দ্র ছিলেন 'ব্যাকরণ অভিধান সাহিত্য নাটক অলঙ্কার সঙ্গীত শাস্ত্রের অধ্যাপক এবং পুরাণ-আগম-পারসী-নাগরী -বেত্তা।'

- ভারতচন্দ্রের জন্মকাল নিয়ে মতানৈক্য আছে। ঈশ্বরগুপ্ত কর্তৃক উল্লেখিত ১৭১২ সাল সঠিক জন্মসাল নয়। বিভিন্ন তথ্য ও অনুমান মিলিয়ে সিদ্ধান্ত করা হয়েছে যে, ভারতচন্দ্র আঠার শতকের গোড়ার দিকে ১৭০৫ থেকে ১৭১০ সালের মধ্যে জন্মগ্রহণ করেছিলেন। ড. আশুতোষ ভট্টাচার্য সর্বশেষ তথ্য বিবেচনা করে ১৭০৭ সালে ভারতচন্দ্রের জন্ম হয়েছিল বলে মনে করেন। রায়গুণাকর ভারতচন্দ্র বর্তমান বর্ধমান বিভাগের ভুরসুট পরগনায় আধুনিক হাওড়া জেলার পেঁড়ো (পান্ডুয়া) গ্রামে জন্মগ্রহণ করেন।

- চল্লিশ বৎসর বয়সে ভারতচন্দ্র নবদ্বীপের রাজা কৃষ্ণচন্দ্র রায়ের সভাকবি নিযুক্ত হন। তাঁর মাসিক বেতন হয় চল্লিশ টাকা। কবি মহারাজ কৃষ্ণচন্দ্রকে প্রতিদিন কবিতা রচনা করে শোনাতেন। তাঁর কবিত্বে মুগ্ধ হয়ে রাজা তাঁকে 'গুণাকর' উপাধি প্রদান করেন এবং প্রচুর ভূসম্পত্তি উপহার দেন।

- ভারতচন্দ্র মহারাজ কৃষ্ণচন্দ্রের আদেশে 'অন্নদামঙ্গল' কাব্য রচনা করেন। কবি গ্রন্থোৎপত্তি সম্পর্কে বলেছেন যে, একদিকে দেবীর আদেশ, অন্যদিকে রাজার আদেশে কাব্য রচনা করেছেন।

অন্যদিকে,
• বিদ্যাপতি ছিলেন মিথিলার কবি। মিথিলার রাজসভার কবি বিদ্যাপতি মৈথিলি ভাষায় সুন্দর পদাবলি ও অন্যান্য গীতিকবিতা রচনা করে সকলকে মুগ্ধ করেছেন বলে তাঁকে 'মৈথিল কোকিল' বলা হয়। তিনি ছিলেন ব্রজবুলি বৈষ্ণব কবি এবং পদসঙ্গীত ধারার রূপকার। তাঁর শ্রেষ্ঠ কীর্তি হচ্ছে ব্রজবুলিতে রচিত রাধাকৃষ্ণ বিষয়ক পদ।

• চণ্ডীদাস চৈতন্যপূর্ব যুগের কবি ছিলেন। চণ্ডীদাসকে বাংলা ভাষার প্রথম মানবতাবাদী কবি বলা হয়।

• মুকুন্দরাম চক্রবর্তীর উপাধি ছিল কবিকঙ্কন।মধ্যযুগের বাংলা সাহিত্যে মানব রসের তিনি প্রথম এবং একমাত্র স্রষ্টা। মুকুন্দরাম চক্রবর্তীকে দুঃখ-বর্ননার কবি হিসাবেও আখ্যায়িত করা হয়।

উৎস: বাংলা সাহিত্যের ইতিহাস, ড. মাহাবুবুল আলম।

• লুইপা:
- 'চয্যাচর্যবিনিশ্চয়'-এর প্রথম কবি লুইপা। তিব্বতি ঐতিহ্যে প্রাপ্ত চুরাশি জন সিদ্ধাচার্যের নামের তালিকায় লুইয়ের নাম আদিতম। অনেক পণ্ডিত লুইপাকে প্রথম চর্যাগীতি রচয়িতা বলে মনে করেন। তাঁর জীবনকাল ৭৩০-৮১০ খ্রিষ্টাব্দের মধ্যে। সে সময় ছিল রাজা ধর্মপালের রাজত্বকাল। হিন্দিভাষীরা লুইপাকে মগধ বা বিহারের অধিবাসী বলে দাবি করেন।

- যোগতন্ত্রশাস্ত্রেও লুইপার উল্লেখ রয়েছে। তন্ত্রশাস্ত্রের লুইপার অন্য নাম মীননাথ বা মৎস্যেন্দ্রনাথ। মৎস্যের সঙ্গে নামের মিল থাকায় কোনো কোনো পণ্ডিত লুইকে শবরপা-এর শিষ্য ও ধীবর সম্প্রদায়ের অন্তর্ভুক্ত বলে উল্লেখ করেন। এ লুইপা আদি সিদ্ধাচার্য (সকল সিদ্ধাচার্যের গুরু) বলে অনেকের ধারণা।

- লুইপাকে সংস্কৃত টীকাকার মুনি দত্ত আদি সিদ্ধাচার্য বলে উল্লেখ করেছেন। তবে, তারানাথের মতে, লুইপা চতুর্থ সিদ্ধাচার্য, আর সরহ হলেন আদি সিদ্ধাচার্য। তাঁর মতে, লুইপা ছিলেন উড্ডীয়ান-রাজ উদয়নের কর্মচারী। তিনি শবর পা-র শিষ্যত্ব গ্রহণ করেছিলেন। চর্যাগীতির লুইপা আর তন্ত্রশাস্ত্রের লুইপা অভিন্ন নয় বলেই মনে করা হয়। কেননা বলা হয়েছে, লুইপা ছিলেন গৌড় অঞ্চলের অধিবাসী। আর তন্ত্রশাস্ত্রের মীননাথ বা মৎস্যেন্দ্রনাথের বাড়ি দক্ষিণবঙ্গে। তিনি ছিলেন গোরক্ষনাথের গুরু। তাই ধারণা করা হয়, লুইপা ও মীননাথ অভিন্ন ব্যক্তি নয়।

- হরপ্রসাদ শাস্ত্রীর ধারণা লুইপা ছিলেন বাঙালি। রাহুল সাংস্কৃত্যায়নের মতে, লুইপা রাজা ধর্মপালের সচিব হিসেবে দায়িত্ব পালন করেন।

- লুইপা বহু গ্রন্থ রচনা করেছেন। তিব্বতি অনুবাদের মাধ্যমে লুইয়ের বৌদ্ধ দর্শন বিষয়ক তিনটি গ্রন্থের নাম পাওয়া যায়। এগুলো হলো: 'শ্রীভগবদভিসময়', 'অভিসময়বিভঙ্গ' ও 'তত্ত্বস্বভাবদোহাকোষগীতিকাদৃষ্টিনাম'। প্রথম দুটি বই দর্শনের এবং তৃতীয়টি দোঁহা ও গানের।

উৎস: বাংলা সাহিত্যের ইতিহাস, ড. মাহাবুবুল আলম।

• মিছিল (বিশেষ্য পদ),
- এটি ফারসি ভাষার শব্দ।
অর্থ:
- শোভাযাত্রা (মহরমের মিছিল)।
- মোকদ্দমা ও তৎসম্বন্ধীয় নথিপত্র।
- বিন্যাস, সিজিল।
- সমান, সমকক্ষ।

• ফারসি ভাষা থেকে আগত কিছু শব্দ হলো:
গ্রেপ্তারি, গ্রেফতার, দারোগা, দারোয়ান, সাদা, খরগোশ, কাজি, খোয়াব, চেহারা, কাগজ, চশমা, চাকর, চারপায়, ছয়লাপ ইত্যাদি।

উৎস: বাংলা একাডেমি, আধুনিক বাংলা অভিধান।

• ধ্বনি:
- ভাষার ক্ষুদ্রতম একক ধ্বনি। কোনো ভাষার উচ্চারিত শব্দকে সূক্ষ্মভাবে বিশ্লেষণ করলে তার যে অবিভাজ্য ক্ষুদ্রতম অংশ পাওয়া যায়, তা-ই ধ্বনি। মানুষের বাগ্‌যন্ত্রের সহায়তায় উচ্চারিত ধ্বনি থেকেই ভাষার সৃষ্টি। বস্তুত ভাষাকে বিশ্লেষণ করলে চারটি মৌলিক উপাদান পাওয়া যায়। এই উপাদানগুলো হলো-ধ্বনি, শব্দ, বাক্য ও অর্থ।

- মানুষ তার মনের ভাব প্রকাশ করার জন্য 'কথা' বলে। মানুষের 'কথা' হলো অর্থযুক্ত কিছু ধ্বনি। ব্যাকরণ শাস্ত্রে মানুষের কণ্ঠনিঃসৃত শব্দ বা আওয়াজকেই ধ্বনি বলা হয়। বস্তুত অর্থবোধক ধ্বনিসমূহই মানুষের বিভিন্ন ভাষার বাধ্বনি। ধ্বনিই ভাষার মূল ভিত্তি।

- ধ্বনি নির্গত হয় মুখ দিয়ে। ধ্বনি উৎপাদনে মুখ, নাসিকা, কণ্ঠ প্রভৃতি বাক্-প্রত্যঙ্গ ব্যবহৃত হলেও ধ্বনি উৎপাদনের মূল উৎস হলো ফুসফুস। ফুসফুসের সাহায্যে আমরা শ্বাস গ্রহণ ও ত্যাগ করি। ফুসফুস থেকে বাতাস বেরিয়ে আসার সময় বিভিন্ন বাক্-প্রত্যঙ্গের সংস্পর্শে আসে। ফুসফুস থেকে বাতাস স্বরযন্ত্রের মধ্য দিয়ে বেরিয়ে আসার সময় মুখের বিভিন্ন জায়গায় ঘষা খায়। এই ঘর্ষণের ফলে মুখে নানা ধরনের ধ্বনির সৃষ্টি হয়।

- অর্থাৎ ফুসফুস নির্গত বাতাস স্বরযন্ত্রের মধ্য দিয়ে মুখগহ্বরে প্রবেশের পর বিভিন্ন বাক্-প্রত্যঙ্গের সংস্পর্শে আঘাত লাগার দরুন ধ্বনি গঠিত বা তৈরি হয়। ধ্বনি গঠনে বিভিন্ন বাক্- প্রত্যঙ্গের ভূমিকা অত্যন্ত গুরুত্বপূর্ণ।

উৎস: বাংলা ব্যাকরণ ও নির্মিতি, সপ্তম শ্রেণি।

• আনা (য়ানা) -আনি (য়ানি) বিদেশি তদ্ধিত প্রত্যয়: ভাব, অভ্যাস বা আচরণ অর্থে বিশেষ্য শব্দ গঠন করে।
যেমন:
ঘর + আনা = ঘরানা,
গরিব + আনা = গরিবানা,
বাবু + আনা = বাবুয়ানা,
বিবি + আনা = বিবিয়ানা ইত্যাদি।

আবার,
বাবু + আনি = বাবুআনি > বাবুয়ানি।

• এরূপ কিছু বিদেশি তদ্ধিত প্রত্যয় হলো-
-ওয়ান, -খানা, -খোর, -গর, -গিরি, -চা > চি, -চী > চি, -তর (তরো), -দান, -দানি, -সার, -নবিশ, -বন্দি, -বাজ /-বাজি, -সহি, সই, -স্তান।

উৎস: ভাষা-শিক্ষা, ড. হায়াৎ মামুদ।

• যুক্তবর্ণের অশুদ্ধ গঠন- ঞ্‌ + ক = ঙ্ক।
- শুদ্ধরূপ: ঙ্‌ + ক = ঙ্ক।

---------------
• যুক্তবর্ণ:
একাধিক বর্ণ যুক্ত হয়ে যুক্তবর্ণ তৈরি হয়। যুক্ত হওয়া বর্ণগুলোকে দেখে কখনো সহজে চেনা যায়, কখনো সহজে চেনা যায় না। এদিক দিয়ে যুক্তবর্ণ দুই রকম: স্বচ্ছ ও অস্বচ্ছ।

গুরুত্বপূর্ণ কিছু যুক্তবর্ণ হলো-
- জ্‌ + ঞ = জ্ঞ;
- ঞ্‌ + জ = ঞ্জ;
- ঞ্‌ + চ = ঞ্চ;
- ঞ্‌ + ছ = ঞ্ছ;
- ষ্‌ + ণ = ষ্ণ।

উৎস: ভাষা-শিক্ষা, ড. হায়াৎ মামুদ।

• বিশেষ্যের জায়গায় বিশেষণের কিংবা বিশেষণের বাহুল্য প্রয়োগজনিত ভুল:
বাক্যের মধ্যে ব্যবহৃত বিশেষ্য পদকে বিশেষণ কিংবা বিশেষণ পদকে বিশেষ্য ভেবে পদ পরিবর্তন করলে এ ধরনের ভুল হয়।
যেমন- আবশ্যক শব্দটি বিশেষণ হিসেবে ব্যবহৃত হয়। এর বদলে ঈয় প্রত্যয় যোগ করে আবশ্যকীয় শব্দের ব্যবহার যথাযথ নয়।
যেমন
অশুদ্ধ: অনাবশ্যকীয় ব্যাপারে কৌতূহল ভালো নয়।
শুদ্ধ: অনাবশ্যক ব্যাপারে কৌতূহল ভালো নয়।

অশুদ্ধ: ইহার আবশ্যক নাই।
শুদ্ধ: হার আবশ্যকতা নাই।

অশুদ্ধ: রাঙ্গামাটি পার্বতীয় এলাকা।
শুদ্ধ: রাঙ্গামাটি পার্বত্য এলাকা।

অশুদ্ধ: বাংলাদেশ একটি উন্নতশীল দেশ।
শুদ্ধ: বাংলাদেশ একটি উন্নয়নশীল দেশ।

উৎস: ভাষা-শিক্ষা, ড. হায়াৎ মামুদ।

• বিশেষণ পদ নয়- সততা।
- 'সততা' গুণবাচক বিশেষ্য পদ।

• আদ্য প্রত্যয় বা উপসর্গযুক্ত বিশেষণ: এ ধরনের বিশেষণ আদ্যপ্রত্যয় বা উপসর্গযোগে গঠিত হয়।
যেমন:
- নিখুঁত (নি + খুঁত) কাজ।
- সুকঠিন (সু + কঠিন) প্রতিজ্ঞা।
- দুঃসহ (দুঃ + সহ) দারিদ্র্য।

উৎস: ভাষা-শিক্ষা, ড. হায়াৎ মামুদ এবং বাংলা একাডেমি, আধুনিক বাংলা অভিধান।

• শুদ্ধ বানান: গৃহস্থ।
- এটি বিশেষ্য পদ।
- সংস্কৃত ভাষার শব্দ।
অর্থ:
- সংসার ধর্ম পালন করে এমন,
- গৃহী।

অন্যদিকে,
• প্রশস্ত, অভ্যস্ত ও ব্যস্ত বানানগুলো শুদ্ধ।

• এরূপ কিছু শুদ্ধ শব্দ- ঠোঁটস্থ, মুখস্থ, দ্বারস্থ, অস্ত, কণ্ঠস্থ, গ্রস্ত।

উৎস: বাংলা একাডেমি, আধুনিক বাংলা অভিধান।

• 'কালো বরফ' উপন্যাস:
- ১৯৭৭ সালের ২১-৩০ আগস্ট মাহমুদুল হক রচনা করেন 'কালো বরফ' উপন্যাসটি, কিন্তু এর প্রকাশকাল অনেক পরে ১৯৯২ সালে।
- এটি ছেচল্লিশের দাঙ্গা ও ১৯৪৭ সালের দেশভাগকে কেন্দ্র করে রচিত।
- উপন্যাসটিতে হিন্দু-মুসলমানের বিরোধ-দাঙ্গা, দ্বেষ-ক্ষোভ এবং মিলন-বিরহ পরিস্ফুটিত হয়েছে।
- উপন্যাসের প্রধান চরিত্র- আব্দুল খালেক।

অন্যদিকে,
-----------------
• 'খেলাঘর' (১৯৮৮): এটি মুক্তিযুদ্ধভিত্তিক উপন্যাস। চরিত্র: রেহানা, মুকল ও ইয়াকুব। ২০০৬ সালে উপন্যাসটির চলচ্চিত্রায়ন করা হয়।

• 'একটি কালো মেয়ের কথা' উপন্যাস: বাংলাদেশের স্বাধীনতা সংগ্রাম নিয়ে রচিত তারাশঙ্কর বন্দ্যোপাধ্যায়ের উপন্যাস- 'একটি কালো মেয়ের কথা'। এটি প্রকাশিত হয় ১৯৭১ খ্রিষ্টব্দে। এটি তাঁর সর্বশেষ উপন্যাস।

• "কালো ঘোড়া" লেখক ইমদাদুল হক মিলন রচিত একটি উপন্যাস। ১৯৮১ সালে পশ্চিম জার্মানির সিনডেল ফিঙেন শহরে বসে তিনি এই উপন্যাসটি রচনা করেন এবং এটি বাংলাদেশের একটি নিবিড় গ্রামকে কেন্দ্র করে আবর্তিত হয়। ‘কালোঘোড়া’ মুক্তিযুদ্ধের উপন্যাস। ১৯৭১ এর সেই জেগে ওঠার দিনে বাংলাদেশের একটি গ্রামে কেমন চেহারা নিয়েছিল মুক্তিযুদ্ধ, কেমন করে মুক্তিযুদ্ধ প্রভাবিত করেছিল গ্রামের প্রতিটি মানুষকে, কেমন করে মুক্তিযোদ্ধারা এসে আশ্রয় পায় এক বালকের কাছে, কেমন করে প্রাণ হারায় এব বোবা যুবতী, স্বাধীনতা বিরোধী চক্রের হোতা কেমন করে নিহত হয় মুক্তেোদ্ধাদের হাতে আর কেমন করেই বা মুক্তিযোদ্ধাদের আশ্রয়দাতা সেই বালক নিজের অজান্তে হয়ে ওঠে এক মহান মুক্তিযোদ্ধা, প্রাণের বিনিময়ে যে রক্ষা করতে চায় সহযোদ্ধাদের কে, এরকম অনেকগুলো বিষয়কে ‘কালোঘোড়া’ উপন্যাসে উপজীব্য করেছেন ইমদাদুল হক মিলন।

উৎস: 'কালো বরফ' ও "কালো ঘোড়া" উপন্যাস; বাংলা ভাষা ও সাহিত্য জিজ্ঞাসা এবং বাংলাপিডিয়া।

• 'বিসর্জন' নাটক:
- 'বিসর্জন' রবীন্দ্রনাথ ঠাকুর রচিত একটি নাটক। 'রাজর্ষি' উপন্যাসের প্রথমাংশ অবলম্বনে 'বিসর্জন' নাটকটি রচিত হয়।

- 'বিসর্জন' রবীন্দ্রনাথ ঠাকুরের মঞ্চসফল এবং জনপ্রিয় নাটকগুলির অন্যতম। রবীন্দ্রনাথ ঠাকুর স্বয়ং এই নাটকের প্রধান দুটি চরিত্র রঘুপতি ও জয়সিংহের ভূমিকায় বিভিন্ন সময়ে অভিনয় করেন।

- উদার ধর্মবোধ এবং সংকীর্ণ ধর্মীয় বিশ্বাসের মধ্যে দ্বন্দ্ব যেমন এই নাটকের প্রধান উপকরণ, তেমনই বিশ্বাসের উগ্রতা এবং মানব সম্পর্কের নিবিড়তা এই নাটকের প্রধান বৈশিষ্ট্য।
- রবীন্দ্রনাথ রচিত বিসর্জন নাটকে গোমতী নদীর কথা উল্লেখ আছে। নাটকটি অমিত্রাক্ষর ছন্দে রচিত।

উল্লেখযোগ্য চরিত্র:
- রঘুপতি,
- জয়সিংহ,
- অপর্ণা,
- গুণবতী,
- গোবিন্দমাণিক্য।

অন্যদিকে,
• 'ডাকঘর' নাটকের উল্লেখযোগ্য চরিত্র: অমল, সুধা, ঠাকুর্দা প্রমুখ।
• 'মুক্তধারা' নাটকের উল্লেখযোগ্য চরিত্র: অভিজিৎ, রণজিত, সুমন, অম্বা, বিভূতি।
• "প্রায়শ্চিত্ত" নাটকের চরিত্রগুলো: ধনঞ্জয়, সুরমা, উদয়াদিত্য, বিভা ইত্যাদি।

-------------------
তাঁর রচিত উল্লেখযোগ্য নাটক:
- রুদ্র চন্দ্র,
- বাল্মিকী প্রতিভা,
- কালের যাত্রা,
- তাসের দেশ,
- ডাকঘর,
- মালিনী ইত্যাদি।

উৎস: বাংলা ভাষা ও সাহিত্য জিজ্ঞাসা এবং বাংলাপিডিয়া।

• ফিলিস্তিনকে স্বীকৃতি:
- ২১ সেপ্টেম্বর, ২০২৫ যুক্তরাজ্য, কানাডা, অস্ট্রেলিয়া ও পর্তুগাল ফিলিস্তিনকে স্বীকৃতি দিয়েছে।
- বিশ্বের ধনী দেশগুলোর জোট জি-৭-এর সদস্যদের মধ্যে প্রথম ফিলিস্তিনকে স্বীকৃতি দিল যুক্তরাজ্য ও কানাডা।
- এর পর দিন ২২ সেপ্টেম্বর, ২০২৫ জাতিসংঘের সদর দপ্তর এক অনুষ্ঠানে ফিলিস্তিনকে আনুষ্ঠানিকভাবে রাষ্ট্র হিসেবে স্বীকৃতি দিয়েছে জাতিসংঘের নিরাপত্তা পরিষদের স্থায়ী সদস্য দেশ ফ্রান্স।
- এ নিয়ে জাতিসংঘের ১৯৩ সদস্যদেশের দেড় শ’র বেশি দেশ ফিলিস্তিনকে রাষ্ট্র হিসেবে স্বীকৃতি দিয়েছে।
- এর মধ্যে এশিয়া, আফ্রিকা, লাতিন ও মধ্য আমেরিকার দেশই বেশি।
- ১৯৮৮ সালের ১৬ নভেম্বর ফিলিস্তিনকে স্বীকৃতি দেয় বাংলাদেশ।
- জাতিসংঘের নিরাপত্তা পরিষদের স্থায়ী পাঁচ সদস্যের মধ্যে ফিলিস্তিন রাষ্ট্রকে এ পর্যন্ত শুধু যুক্তরাষ্ট্র স্বীকৃতি দেয়নি।

সূত্র- প্রথম আলো পত্রিকা প্রতিবেদন।

• ফেডারেল সিভিল সার্ভিস কমিশন:
- মার্কিন যুক্তরাষ্ট্রে সংবিধিবদ্ধভাবে ফেডারেল সিভিল সার্ভিস কমিশন গঠিত হয় ১৮৮৩ সালে।
- The Pendleton Civil Service Reform Act-1883 এর মাধ্যমে।
- ১৯৭৮ সালে ফেডারেল সিভিল সার্ভিস কমিশনে সংস্কার করে একে তিনটি প্রতিষ্ঠানে বিকেন্দ্রীকরণ করা হয়। এগুলো হলো:
- অফিস অব দ্য পার্সোনেল ম্যানেজমেন্ট
- দ্য মেরিট সিস্টেম প্রোটেকশন বোর্ড
- দ্য ফেডারেল লেবার রিলেশন অথরিটি।

উৎস: অফিস অব দ্য পার্সোনেল ম্যানেজমেন্ট ওয়েবসাইট।

• জাপাদ-২০২৫:
- জাপাদ-২০২৫ হলো রাশিয়া ও বেলারুশের যৌথ সামরিক মহড়া।
- এই মহড়া ১২ সেপ্টেম্বর, ২০২৫ শুরু হয় এবং ১৭ সেপ্টেম্বর, ২০২৫ শেষ হয়।
- এই মহড়ায় প্রায় ১ লাখ সেনা অংশগ্রহণ করে, যার মধ্যে ভারী অস্ত্র, বোমারু বিমান, যুদ্ধজাহাজ এবং প্যারাট্রুপারদের সমন্বয়ে ব্যাপক সামরিক কৌশল প্রদর্শন করা হয়।
- যুক্তরাষ্ট্রসহ ২৩টি দেশের প্রতিনিধিরা মহড়া দেখতে বেলারুশে উপস্থিত ছিলেন।
- মহড়ার মূল উদ্দেশ্য ছিল সীমান্তবর্তী অঞ্চলে সম্ভাব্য আগ্রাসন প্রতিহত করার জন্য প্রস্তুতি প্রদর্শন।

তথ্যসূত্র- প্রথম আলো পত্রিকা প্রতিবেদন।