3.2b Input & Output Devices — Edexcel 1CP2

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Input Devices

Input devices send data into the computer. They convert user actions or real-world data into digital signals the CPU can process.

Device	How it works	Common use
Keyboard	Key presses detected, converted to ASCII/Unicode	Text input
Mouse	Movement and clicks detected via optical sensor or ball	GUI navigation
Touchscreen	Capacitive: detects electrical signal from finger	Smartphones, tablets
Barcode reader	Laser scans bars, reflects light pattern decoded	Retail, libraries
QR code scanner	Camera captures 2D matrix, decoded by software	Payments, URLs
Scanner (flatbed)	Light source and sensors capture image of document	Digitising documents
Microphone	Sound waves converted to electrical signal → digital	Voice input, recording
Digital camera	Light hits photosensors (CCD/CMOS), converted to pixel data	Photography, video
Biometric sensor	Reads fingerprint, iris, or face features	Security, login

Output Devices

Output devices receive data from the computer and present it to the user in a usable form.

Device	How it works	Common use
Monitor (LCD)	Pixels lit by backlight through liquid crystals	Visual display
LED/OLED screen	Each pixel emits light individually (OLED)	TVs, phone screens
Inkjet printer	Sprays tiny ink droplets onto paper	Home, photo printing
Laser printer	Laser draws onto drum, toner adheres and transfers	Office, high volume
3D printer	Layers of material (plastic, resin) built up from model	Prototyping, manufacturing
Speakers	Electrical signals converted to sound waves via cone	Audio output
Projector	Displays image on screen via light through lens	Presentations, classrooms
Actuators	Convert electrical signal to physical movement	Robotics, control systems

Input vs Output vs Both

Some devices are both input and output (I/O devices):

Touchscreen — input (touch) and output (display)
Headset — input (microphone) and output (speakers)
Optical drive — input (read disc) and output (write/burn disc)

Choosing Input/Output Devices

Edexcel exam questions often ask you to "suggest a suitable input/output device for a scenario" and justify it. Key points:

Accuracy: barcode reader vs manual keyboard entry
Speed: laser printer faster than inkjet for bulk
Environment: touchscreen in a factory (gloves?), voice control for hands-free
Cost: inkjet cheaper upfront, laser cheaper per page

Exam tip: Always match the device to the scenario. If asked for an input device "in a supermarket checkout", say "barcode scanner" and explain "because it is fast and accurate, reducing human error at checkout." Just naming a device without justification will not get full marks.

⚠️ Common Mistakes

Saying a touchscreen is only an output device — it is both input and output
Confusing inkjet (sprays ink) and laser (uses toner and a drum)
Forgetting to justify device choice in exam scenarios
Calling a monitor an input device — it is output only

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Worksheet — 3.2b Input & Output Devices

8 Edexcel-style questions · instantly marked

Q1State the difference between an input device and an output device.[2]

✅ Mark scheme

An input device sends data into the computer [1]; an output device receives data from the computer and presents it to the user [1].

Q2Explain how a touchscreen is both an input and an output device.[2]

✅ Mark scheme

It acts as an input device because it detects touch from the user [1]; it also acts as an output device by displaying images/information on the screen [1].

Q3A supermarket wants to speed up checkouts. Suggest an input device and justify its use.[2]

✅ Mark scheme

Barcode scanner / barcode reader [1]; because it automatically reads product codes quickly and accurately, reducing human error and speeding up the checkout process [1].

Q4State two differences between an inkjet printer and a laser printer.[2]

✅ Mark scheme

Any two: inkjet sprays liquid ink, laser uses toner powder and a drum [1]; laser is faster [1]; inkjet is cheaper upfront, laser has lower cost per page [1].

Q5Name one biometric input device and give one use for it.[2]

✅ Mark scheme

Any one: fingerprint scanner [1] used to unlock a phone/computer [1]; iris scanner [1] used for high-security access control [1]; facial recognition camera [1] used for phone unlock or border control [1].

Q6A hospital needs to input patient forms from paper records into a computer quickly. Suggest a suitable input device.[2]

✅ Mark scheme

Flatbed scanner [1]; because it digitises paper documents quickly and accurately, producing a digital image of the form [1].

Q7What is an actuator and give one example of its use?[2]

✅ Mark scheme

An actuator is an output device that converts an electrical signal into physical movement [1]; used in robotics/control systems, e.g. a robot arm in manufacturing [1].

Q8Explain how a microphone converts sound into digital data.[3]

✅ Mark scheme

Sound waves cause a diaphragm to vibrate [1]; this generates an analogue electrical signal [1]; an ADC (analogue-to-digital converter) converts the signal to digital data [1].

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Input Devices

Output Devices

Input vs Output vs Both

Choosing Input/Output Devices

Worksheet — 3.2b Input & Output Devices

Mini Test — Input & Output