IGCSE Computer Science Paper 1 Definitions Worksheet: 3.2 Input and Output Devices (Modules 252–261)
Name:
Date:
Class:
✎
Key terms
Write what each term means, in your own words.
1
barcode scanner
2
QR code scanner
3
1D barcode vs 2D QR code
4
touch screen
5
resistive touch screen
6
capacitive touch screen
7
infra-red touch screen
8
resistive, capacitive, infra-red
9
2D scanner
10
3D scanner
Answer Key
IGCSE Computer Science Paper 1 · Modules 252–261 · Student wording will vary for definitions
1barcode scanner — An input device that shines a laser across a barcode. Black lines absorb light, white gaps reflect it, and a sensor reads the pattern to get the product number.
2QR code scanner — Uses a camera to capture a 2D square grid of black and white modules and decodes it into data like a web address or text. It holds more data than a barcode and reads from any angle.
31D barcode vs 2D QR code — A barcode stores a short number in one dimension of lines; a QR code stores much more data in two dimensions of squares and can be read by a camera from any angle.
4touch screen — A display that is also an input device: it detects where a finger or stylus touches it. Types are resistive, capacitive and infra-red. Used in phones, tablets, kiosks and ticket machines.
5resistive touch screen — A screen with two conductive layers that touch when pressed; the change in resistance at the touch point gives its position. Works with finger, glove or stylus.
6capacitive touch screen — A touch screen with a charged glass layer. A finger conducts electricity and changes the charge at the touch point, so its position is found. Supports multi-touch.
7infra-red touch screen — A screen with a grid of infra-red beams across it. A touch breaks beams, and the broken x and y beams give the touch position. Works with any object.
8resistive, capacitive, infra-red — Resistive senses pressure on layers; capacitive senses a finger's electric charge; infra-red senses a broken light beam. How touch is detected decides which device each suits.
92D scanner — An input device that moves a light and sensor across a flat page or photo, reading the reflected light to capture a digital image made of pixels.
103D scanner — An input device that uses lasers, light patterns or cameras to measure many points on an object's surface and combine them into a digital 3D model of its shape.