Which of the following devices is not considered an output device in a computer system?

Introduction / Context:
This question checks understanding of basic input and output devices in a computer system. Output devices are hardware components that present information from the computer to the user in visual, printed or audio form. Input devices send data to the computer for processing. Many exam questions present mixed lists of devices and ask which one does not belong to a given category. Correct classification of devices like scanners, monitors and printers is important for foundational computer literacy.

Given Data / Assumptions:

• The question asks which device is not an output device.
• Options include scanner, monitor, printer, speakers and projector.
• We assume standard definitions where output devices convey information from the computer to the outside world.
• Input devices capture data from the user or environment and send it into the computer.

Concept / Approach:
Monitors, printers, speakers and projectors are classic output devices. A monitor displays visual information, a printer produces printed output on paper, speakers play audio and projectors show enlarged images. A scanner, on the other hand, takes physical documents or images and converts them into digital form that is sent into the computer. This makes the scanner an input device rather than an output device. Therefore, when asked which listed device is not an output device, the correct choice is the scanner.

Step-by-Step Solution:

Verification / Alternative check:
Introductory computer textbooks group devices into input and output categories. Scanners are consistently listed under input devices together with keyboards, mice and microphones. Output devices are listed as monitors, printers, speakers and projectors. Some diagrams show the computer in the centre with arrows indicating data flow from scanner to computer and from computer to monitor and printer. This consistent classification confirms that the scanner is not an output device but an input device, making it the correct answer to the question.

Why Other Options Are Wrong:

• Monitor: Clearly an output device because it displays text and graphics generated by the computer.
• Printer: Produces a physical printed copy of digital documents, which is a form of output.
• Speakers: Output device that converts digital audio signals into audible sound.
• Projector: Output device that projects the computer display onto a larger screen or wall.

Common Pitfalls:
Some learners confuse input and output roles for devices that handle images, such as scanners and projectors. A simple rule to avoid confusion is to think about the direction of information flow. If information goes from the physical world into the computer, it is an input device. If information flows from the computer to the user in visible or audible form, it is an output device. Applying this rule clearly shows that scanners are input devices and should be chosen when asked which one is not an output device in a list dominated by monitors, printers and speakers.

Final Answer:
The device that is not an output device is the Scanner, which is an input device.