Output devices and their uses

A benefit is true of the device on its own; an advantage is true only against a named alternative. The examiners' example is a printer: "the laser printer produces a good-quality printout" is a benefit and earns nothing on an advantage question; "produces a better-quality printout than a dot matrix printer" scores: it has a comparative and names what it beats.

A laser printer's high purchase price and costly toner are genuine characteristics of the device. But examiners rule cost, battery life and storage capacity too subjective on device comparisons, and no longer credit them as technology improves — so "cheaper to run" is true but scores nothing as an advantage. Compare speed, print quality, noise or capability instead.

The touch screen is examined twice. In 2.1 it is an input device — it detects where and how the surface was touched. Here in 2.3 it is an output device — it displays the image, text, menus and buttons the user sees. Describing the pressing action when the output role was asked answers the wrong half: output is what is shown, not what is detected.

An actuator does not measure anything. It receives a signal the computer has already processed and produces a physical action out — opening a vent, turning a motor. An answer describing an actuator taking a reading reverses the direction of flow. In a monitoring-and-control question name both halves: the sensor supplying data in, the actuator carrying the action out.

Naming an output device is not enough — the reason must be tied to the data or the scenario. Candidates asked which output device an automated glasshouse used gave general answers instead of a specific device. "Use a screen" or "print it" is too vague; "a monitor, because the numerical readings can be read directly" is what the mark scheme wants.

A plotter draws large, accurate technical lines with pens — valuable for design documentation, but flat. A prototype has to be handled and test-fitted, so it needs a 3D printer, which builds a physical object layer by layer from the digital model. Choosing on "large and accurate" alone, without asking what a prototype actually requires, picks the wrong device.

"It could hurt someone" is too vague to credit. Name the hazard and its cause: staring at the strong, bright projected light causes eye problems or headaches, because the light is far more intense than a monitor's; and the projector's loose trailing cables are a tripping hazard, or the unit itself can fall and injure someone where people walk past.