Input/Output — Set 3

Correct Answer: A. Toggle Keys

• **Toggle Keys** = keys that switch a specific mode on with the first press and off with the next press, acting like a light switch — Caps Lock toggles between uppercase and lowercase letter input, and Num Lock switches the numeric keypad between number entry and cursor navigation. • **Indicator lights** — keyboards typically have small LED lights labelled Caps Lock, Num Lock, and Scroll Lock to show which toggles are currently active, so users always know the current mode. • Scroll Lock, though rarely used today, was originally designed to toggle the behaviour of the arrow keys in spreadsheet applications. • 💡 Option B (Function Keys) is wrong because function keys (F1–F12) trigger specific software commands and are not on/off toggles; Option C (Modifier Keys) is wrong because modifier keys like Shift, Ctrl, and Alt only change the meaning of another key while held down and do not latch on independently; Option D (Navigation Keys) is wrong because navigation keys (arrow keys, Home, End, Page Up/Down) move the cursor position, not toggle modes.

Correct Answer: C. Multimedia Projector

• **Multimedia Projector** = an output device that receives the video signal from a computer, passes it through a powerful light source and lens system, and projects a magnified image onto a distant screen or wall — this allows an entire audience to view the same content simultaneously. • **Brightness measured in lumens** — projector brightness is rated in ANSI lumens; a classroom projector typically needs 3,000–4,000 lumens, while outdoor events may require 10,000+ lumens to overcome ambient light. • Modern projectors use DLP (Digital Light Processing) or LCD panels and support wireless screen mirroring via Wi-Fi. • 💡 Option A (Plotter) is wrong because a plotter draws large-format vector graphics on paper and produces no projected image; Option B (CRT Monitor) is wrong because a CRT monitor is a personal desk display viewed by one or a few people, not projected for a large audience; Option D (Scanner) is wrong because a scanner is an input device that reads physical documents and cannot project any image.

Correct Answer: D. Graphics Tablet

• **Graphics Tablet** = a pressure-sensitive flat input device paired with a stylus — as the artist draws on the tablet surface, sensors detect the stylus position, pressure level, and tilt angle, translating each stroke into digital brush strokes with variable thickness and opacity that mirror the feel of real drawing on paper. • **Pressure sensitivity** — a professional graphics tablet (e.g., Wacom Intuos) can detect 8,192 levels of pen pressure, allowing an artist to create thin hairlines with a light touch and thick fills with heavy pressure, something a mouse cannot replicate. • Graphics tablets are the standard tool for digital illustrators, photo retouchers, and animators in the creative industry. • 💡 Option A (Mouse) is wrong because a mouse controls cursor position on a flat surface but cannot detect pressure or tilt, making fine artistic strokes impossible; Option B (Scanner) is wrong because a scanner reads existing physical documents, it does not allow real-time drawing input; Option C (Touchscreen) is wrong because while touchscreens accept finger or stylus input, they lack the dedicated pressure sensitivity and large surface area needed for professional digital art.

Correct Answer: A. To capture an image of the current screen

• **Capture an image of the current screen** = pressing the Print Screen (PrtSc) key takes an instant snapshot of everything currently displayed on the monitor and copies it to the Windows clipboard as a bitmap image — the user can then paste it into Paint, Word, or any image editor to save or annotate it. • **Modern variations** — in Windows 10/11, pressing Win + Shift + S activates the Snipping Tool for selective screenshots; pressing Win + PrtSc saves the screenshot directly as a PNG file in the Screenshots folder without needing to paste. • The key is named Print Screen because on early computers it was used to send the screen contents to the printer directly. • 💡 Option B (To send a file to the printer) is wrong because sending to a printer uses Ctrl+P or the Print command from an application's menu; Option C (To turn off the monitor) is wrong because monitors are turned off with their own power button or display settings; Option D (To clean the printer head) is wrong because printer head cleaning is a hardware maintenance function accessed through the printer's own utility software.

Correct Answer: C. Capacitive or Resistive

• **Capacitive or Resistive** = touchscreens use one of two technologies to detect a finger touch — capacitive screens detect the tiny electrical charge from the human body's skin (no physical pressure needed), while resistive screens detect physical pressure when two flexible conductive layers are pressed together. • **Why capacitive dominates** — capacitive screens on smartphones support multi-touch gestures (pinch-to-zoom, two-finger rotate) and respond to the lightest tap, whereas resistive screens require deliberate pressure and respond to any object (including a stylus or gloved finger) but support only single touch. • Most modern smartphones, tablets, and ATM screens use projected capacitive (PCAP) technology. • 💡 Option A (Mechanical) is wrong because mechanical sensing involves physical moving parts like buttons, not flat glass screen surfaces; Option B (Acoustic) is wrong because acoustic wave touchscreens exist but are specialised, fragile, and not used in mainstream consumer devices; Option D (Magnetic) is wrong because magnetic fields are used in stylus digitisers (like on drawing tablets) and are not the standard touch-detection method in consumer touchscreen devices.

Correct Answer: D. PPM

• **PPM (Pages Per Minute)** = the standard unit for measuring printer output speed, indicating how many full A4 or Letter-size pages a printer can produce in sixty seconds under typical conditions — a home inkjet printer might achieve 10–20 PPM, while office laser printers often reach 30–60 PPM. • **DPI vs PPM** — DPI (Dots Per Inch) measures print quality or resolution (how sharp the output looks), while PPM measures throughput speed; they are completely different metrics that both appear on printer spec sheets. • Commercial production printers can exceed 100 PPM, enabling high-volume publishing of newspapers and direct-mail flyers. • 💡 Option A (DPI) is wrong because DPI measures print resolution (sharpness), not speed; Option B (Bits) is wrong because bits measure digital data size, not paper output rate; Option C (Baud) is wrong because Baud measures data transmission rate in communication systems, not printing speed.

Correct Answer: A. Joystick

• **Joystick** = a multi-axis input device with a pivoting stick and multiple programmable buttons designed to replicate the physical controls of an aircraft cockpit — in flight simulators it controls pitch, roll, and yaw, making it far more intuitive for aviation-style navigation than any other peripheral. • **Buttons and throttle** — high-end flight joysticks include a throttle lever, hat switch for view control, rudder twist, and 20+ programmable buttons, all mapped to in-game controls to create an immersive simulation experience. • Joysticks have been used since the early 1980s in arcade cabinets (Pac-Man, Galaga) before becoming standard for PC flight and space simulators. • 💡 Option B (Light Pen) is wrong because a light pen is used to point at or draw on a CRT screen surface, not to simulate aircraft controls; Option C (Trackball) is wrong because a trackball is a cursor-pointing device rolled by the thumb and offers no multi-axis flight control; Option D (Scanner) is wrong because a scanner is an input device that digitises documents and has no gaming or simulation function.

Correct Answer: C. To convert scanned text images into editable text

• **Convert scanned text images into editable text** = OCR software analyses a raster image of a printed or handwritten page, identifies the shape of each character using pattern-matching algorithms, and outputs a fully editable text string — turning a JPG photo of a book page into a Word document, for example. • **How it works** — the OCR engine preprocesses the image (straightens skew, removes noise), segments it into lines, words, and characters, then matches each character's shape against a trained model to determine the most likely letter or digit. • OCR powers Google Lens, searchable PDFs, automated invoice processing, and digitisation of historical archives. • 💡 Option A (To print characters) is wrong because printing is the function of a printer, not OCR software; Option B (To recognize human faces) is wrong because facial recognition uses different AI algorithms (facial geometry analysis), not character-shape matching; Option D (To check for viruses) is wrong because antivirus software scans executable code for malware signatures, a completely unrelated function.

Correct Answer: D. Headphones

• **Headphones** = compact output devices worn on or over the ears that deliver audio privately to a single user — because they direct sound into the ear canals only, no one nearby can hear the playback, making them ideal for private music listening, gaming, or studying in shared spaces. • **Over-ear vs in-ear** — over-ear (circumaural) headphones cup the entire ear for passive noise isolation; in-ear (earbuds) fit inside the ear canal; wireless versions use Bluetooth A2DP profile to connect without cables. • Noise-cancelling headphones use microphones and DSP chips to generate anti-phase sound waves that actively cancel ambient noise. • 💡 Option A (Speaker) is wrong because speakers broadcast sound outward for everyone in the room to hear, the opposite of private listening; Option B (Microphone) is wrong because a microphone is an input device that captures sound from the environment; Option C (Sound Card) is wrong because the sound card is an internal component that processes and routes audio signals, it is not worn or used for direct listening.

Correct Answer: A. Touch Screen

• **Touch Screen** = the only common device on this list that serves as both input and output — it outputs information by displaying images, text, and video on its screen, and simultaneously accepts input by detecting the position of a finger or stylus touch on that same surface. • **Dual-layer design** — physically, a touchscreen has an underlying display panel (LCD/OLED) for output layered with a transparent touch sensor (capacitive or resistive) for input, both working together in a single integrated unit. • ATMs, smartphones, tablets, POS terminals, and self-service kiosks all rely on this dual input-output functionality to create compact, interactive interfaces without a separate keyboard or mouse. • 💡 Option B (Scanner) is wrong because a scanner is purely an input device that converts physical documents to digital images — it has no display or output function; Option C (Printer) is wrong because a printer is purely an output device that puts ink on paper — it receives data but cannot send any back; Option D (Keyboard) is wrong because a keyboard is purely an input device — it sends keystrokes to the computer but displays nothing.