Raj Computre Institute, Rawanwadi

  1. Resistor (प्रतिरोधक) Definition: A resistor opposes (resists) the flow of electric current in a circuit. Symbol: zig-zag line or rectangle Unit: Ohm (Ω) Functions: Limits current Reduces voltage Protects components Used in LED circuits, voltage dividers, etc. Example: Fan speed regulator, LED resistor 2. Capacitor (संधारित्र) Definition: A capacitor stores electrical energy in the form of an electric field. Symbol: Two parallel plates Unit: Farad (F) Functions: Stores and releases charge Smooths power supply (filters) Used in timing circuits Removes noise Used in fan (motor start capacitor) Example: Fan capacitor, camera flash, SMPS power supply 3. Coil / Inductor (कुंडली / इंडक्टर) Definition: A coil (inductor) stores energy in a magnetic field when current flows through it. Unit: Henry (H) Functions: Blocks AC, allows DC Used in transformers Noise filtering Boost converters (voltage conversion) Examp...

  Concepts of A/C and D/C Current & Flow of Current 1. What is Electric Current? Electric current is the flow of electric charge (electrons) through a conductor like a wire. Measured in Amperes (A) Flows from positive (+) to negative (–) terminal (conventional current) Electrons actually move from negative (–) to positive (+) (electron flow) 2. DC (Direct Current) Definition: DC is the type of current that flows in only one direction . Key Points: Voltage remains constant . Electrons move steadily from – to + . Used in batteries, mobile phones, laptops, solar panels, etc. Examples: Battery Power bank Mobile charger (internal output is DC) Solar cell Waveform: Straight line (constant level on a graph) 3. AC (Alternating Current) Definition: AC current changes direction repeatedly — many times per second. Key Points: Voltage keeps rising and falling in a wave-like pattern. Electrons move back and forth. Used in home...

  Roles & Responsibilities of a Cyber Security Expert 1. Monitoring & Protecting Systems Continuously monitor networks, servers, and systems for suspicious activity. Detect and block unauthorized access, malware, and cyber threats. 2. Implementing Security Measures Install and configure firewalls, antivirus, intrusion detection systems, and security tools. Update systems regularly to protect against new vulnerabilities. 3. Conducting Risk Assessments Identify potential security risks in an organization. Analyze weaknesses and suggest measures to minimize risk. 4. Incident Response & Investigation Respond quickly to cyber-attacks or security breaches. Investigate how the attack happened and prevent it from happening again. 5. Security Audits & Compliance Perform regular audits of networks and systems. Ensure the organization follows security laws, standards, and policies. 6. Data Protection Implement strong encryption ...

  ✅ Difference Between Cyber Crime and Cyber Security Cyber Crime Cyber Security Cyber Crime means illegal activities done using computers, networks, or the internet. Cyber Security means protecting computers, networks, and data from attacks. It focuses on crimes like hacking, phishing, online fraud, cyberbullying, etc. It focuses on preventing these crimes using tools and techniques. Criminals perform cyber crimes to steal data, money, or to harm someone. Security professionals work to detect, stop, and fix security threats. It causes damage to people, companies, and government systems. It reduces damage by creating strong security systems and protections. Cyber Crime is an offensive act (attack). Cyber Security is a defensive act (protection). Example: Hacking a bank account. Example: Using firewalls, antivirus, strong passwords to protect accounts.

  ✅ Categories of Cyber Crimes (English) 1. Hacking Unauthorized access to a computer, mobile, network, or online account. 2. Phishing Fake emails, messages, or websites created to steal personal information such as passwords or banking details. 3. Identity Theft Using someone else’s personal information illegally (Aadhaar, PAN, phone number, etc.). 4. Cyber Fraud / Online Scam Online money-related scams like fake shopping sites, OTP fraud, investment scams, UPI fraud. 5. Cyberbullying / Online Harassment Abusive messages, threatening posts, trolling, or defaming someone online. 6. Ransomware Attack A type of malware that locks your computer or data and demands money to unlock it. 7. Malware Attack Introduction of harmful software like viruses, trojans, and worms to damage systems. 8. Data Breach Unauthorized access or leakage of sensitive data from a company or individual. 9. Cyber Stalking Repeatedly following or tracking someone online through messages,...

  Multimedia What is Multimedia? Multimedia refers to the use of multiple types of media together in a single system or application. It combines: Text Images Audio Video Graphics Animation Multimedia makes communication interactive, attractive, and easy to understand . Elements of Multimedia Text – written information Images – photos, graphics Audio – sound, music, voice Video – moving visual content Animation – moving graphics Interactivity – user control (buttons, menus) Types of Multimedia 1. Linear Multimedia Content plays in a sequence. User cannot control the flow. Examples: Movies TV shows Slideshows (auto-play) 2. Non-Linear Multimedia User can control the content (play, pause, navigate). Examples: Video games Websites Educational apps YouTube 3. Interactive Multimedia User interacts with the system and controls multimedia content. Examples: ATM machines E-learning apps Onl...

  Antivirus Software What is Antivirus? Antivirus is a security software designed to: Detect Prevent Remove Viruses, malware, spyware, ransomware, trojans, worms, and other malicious programs from a computer or mobile device. Antivirus keeps your system safe by scanning files, detecting threats, and removing harmful software. Functions of Antivirus Software ✅ 1. Virus Detection Scans files, programs, and memory to identify known and unknown viruses. ✅ 2. Virus Removal Deletes or repairs infected files to remove viruses. ✅ 3. Real-Time Protection Monitors system activities continuously to block threats instantly. ✅ 4. Scheduled Scans Allows users to set daily, weekly, or monthly automatic scans. ✅ 5. Firewall Protection Blocks unauthorized access to your computer and network. ✅ 6. Email Protection Scans email attachments to detect phishing, spam, or infected files. ✅ 7. Web Protection Warns or blocks harmful websites to protect users from online thr...

  Computer Virus What is a Computer Virus? A computer virus is a malicious program designed to: Damage data Corrupt files Slow down the system Spread from one computer to another It attaches itself to programs, files, or the operating system and spreads when the infected file or program is executed. Characteristics of a Computer Virus Small malicious program Reproduces itself (self-replicates) Can damage or delete data Spreads through USB, email, internet, apps Reduces system performance Works without user permission How Viruses Spread? Infected USB drives Downloading infected software Email attachments Visiting harmful websites File sharing networks Types of Computer Viruses Below are the major types explained clearly: 1. File Infector Virus Infects .exe , .com , and other executable files. Activates when the infected file is opened. Examples: Jerusalem Virus Cascade Virus 2. Boot Sector Virus Infects t...

  Mobile Apps (Mobile Applications) What is a Mobile App? A mobile app (mobile application) is a software program designed to run on mobile devices such as: Smartphones Tablets Smartwatches Mobile apps are developed for specific operating systems like Android , iOS , or Windows Mobile . Features of Mobile Apps Easy to install and use Provide specific functions (calling, chatting, gaming, banking, etc.) Use smartphone features (camera, GPS, sensors, internet) Portable and works anywhere Often supports offline mode Small in size compared to computer software Types of Mobile Apps 1. Native Apps Apps developed specifically for one platform (Android OR iOS). Examples: WhatsApp (Android/iOS versions built separately) Instagram Paytm Advantages: Fast performance Uses device hardware effectively More stable Disadvantages: Expensive to build (separate app for each platform) 2. Web Apps Apps that run on a mobile brow...

  Open Source Software and Proprietary Software 1. What is Open Source Software? Open Source Software (OSS) is software whose source code is freely available to everyone. Anyone can view, modify, distribute, or improve the code. Features of Open Source Software Free to use (mostly) Source code available Community-based development Users can modify and customize Transparent and secure (bugs fixed quickly) Examples of Open Source Software Linux (Operating system) Android Mozilla Firefox VLC Media Player LibreOffice GIMP 2. What is Proprietary Software? Proprietary Software (also called Closed Source Software) is software whose source code is NOT available . Only the company that created it can modify or distribute it. Features of Proprietary Software Usually paid or subscription-based Source code hidden Controlled by a single company Users cannot modify the software Official customer support available Examples of P...

  ⭐ What is Utility Software? Utility Software is a type of system software that helps in the maintenance, protection, and smooth functioning of a computer system . Utility software performs support tasks such as: Virus protection File management System cleanup Backup Compression Disk management 👉 It improves the performance of the computer. 👉 It works along with the Operating System. ⭐ Functions of Utility Software Utility software helps in: Maintaining system health Enhancing performance Securing data Managing files Repairing disks Optimizing storage ⭐ Types of Utility Software Below are the important types: 🔶 1. Antivirus Software Protects computer from viruses, malware, ransomware, spyware. Examples: Quick Heal McAfee Avast Kaspersky Windows Defender 🔶 2. File Compression Software Reduces the size of files for storage and sharing. Examples: WinRAR WinZip 7-Zip Zip/Unzip tools 🔶 3. ...