Basic components of a computer system

Correct answer: A. Webcam and Microphone

Explanation: The governing concept is matching input devices to the type of data they capture. A webcam captures moving visual input, while a microphone captures sound input; together they send video and voice during an online meeting, so option A is correct. A monitor and speaker mainly provide output, a printer and projector display or print information, and a hard disk stores data rather than capturing it.

Correct answer: B. A complete computer system

Explanation: The governing concept is the functional organization of a computer system. Input units enter data, the processing unit works on it, storage keeps data or instructions, and output units present the result. When these units operate together, they form a complete computer system. Option A names only storage, C describes a network, and D refers only to software, so none covers the coordinated hardware functions.

Correct answer: A. Large files must be transferred to an external drive

Explanation: The governing concept is data-transfer bandwidth. USB speed matters when a large amount of digital data must move between the computer and a storage device. A faster compatible USB port can transfer a large video folder or backup in less time, although the drive and cable must also support that speed. Therefore, option A is correct. Cleaning a monitor, changing keyboard colour, and loading printer paper do not involve substantial USB data transfer.

Correct answer: B. It can carry both digital video and audio

Explanation: The governing concept is the type of signal a port carries. HDMI is a digital interface designed to transmit high-quality video and audio through one cable, reducing the need for separate audio connections in many setups. Therefore, option B is correct. It is not primarily a power-only, network-only, or permanent-storage connection. Older video-only interfaces generally required a separate route for sound.

Correct answer: C. It displays output and also accepts input through touch

Explanation: The governing concept is the distinction between input and output devices. A touchscreen displays text, images, menus, and results, so it performs an output function. It also detects a user’s touch and converts that action into commands or selections, so it performs an input function. Hence option C is correct. Storage, sound production, and power supply are not the reason it is called a combined device.

Correct answer: D. Scanning is input and printing is output

Explanation: The governing concept is the direction of information flow. During scanning, the device captures text or an image from a paper document and sends digital information into the computer, so scanning is input. During printing, the computer sends information to the printer, which produces a paper copy, so printing is output. Therefore, option D is correct; option A reverses the directions and B and C classify both functions incorrectly.

Correct answer: C. More dots per inch and generally finer print detail

Explanation: DPI means dots per inch and is a measure of printer resolution. A higher DPI indicates that the printer can place more individual dots within each inch, generally allowing finer detail and sharper-looking text or images. Therefore, option C is correct. Network speed, storage capacity, and sound level describe other computer or device characteristics; none explains DPI. Actual quality can also depend on paper, ink, and image source.

Correct answer: C. Touchscreen

Explanation: The governing concept is the distinction between input and output devices. A touchscreen displays text, images, and controls, so it performs an output function; it also detects a user’s touch and sends that information to the computer, so it performs an input function. Thus option C is correct. A basic speaker produces sound, a keyboard only enters keystrokes, and a printer produces printed output, so those choices do not normally perform both roles.

Correct answer: C. When more devices must be connected than the available USB ports

Explanation: The governing concept is USB port expansion. A USB hub connects to one computer USB port and provides several additional ports, allowing devices such as a keyboard, mouse, storage drive, or camera to be connected when the computer has too few ports. Thus option C is correct. A hub does not replace the CPU, format a hard disk, or control monitor brightness. If many power-hungry devices are attached, a powered hub may be needed.

Correct answer: D. It can carry both digital video and audio through one cable

Explanation: The governing concept is multimedia signal transmission. HDMI is a digital interface designed to carry high-quality video and audio through the same cable, so a separate audio cable is often unnecessary. Option D is correct because it states the principal advantage over a video-only connection. HDMI does not increase storage, perform CPU processing, or merely supply electrical power. Actual supported resolution, refresh rate, and audio formats depend on the devices and HDMI version.

Correct answer: D. Reflection of laser light

Explanation: The governing concept is optical data storage. An optical drive shines a laser onto the disc surface and detects differences in the reflected light caused by microscopic recorded features. The detected pattern is interpreted as digital data. Therefore option D is correct. A magnetic head belongs to magnetic storage such as a hard disk, while a fan and a keyboard have no role in reading an optical disc. CDs and DVDs use this optical reading principle.