Basic components of a computer system

A touchpad is a pointing input device built into most laptops. Moving a finger across its surface controls the on-screen pointer, and tapping or pressing it can select items, so option A is correct. A speaker produces sound, a webcam captures video, and a battery supplies stored electrical energy; none of these controls pointer movement.

A battery stores electrical energy and supplies it to the laptop when the charger is not connected, allowing portable operation; therefore, option B is correct. A hard disk stores files, a monitor displays information, and a touchpad accepts pointing input. These components may be essential for other tasks, but they do not provide the laptop’s independent power source.

A touchscreen combines two functions: it displays text, images, and video as an output device, while its touch-sensitive surface receives taps, swipes, and other commands as an input device. Therefore, option C is correct. Calling it only input ignores the display, while calling it only output ignores touch control; it is not a storage component.

The buttons, joystick, and triggers on a game controller convert the player’s actions into commands sent to a computer or game console. Thus, it mainly provides user input signals, making option D correct. A monitor produces visual output, a printer produces printed output, and storage devices retain data; the controller primarily captures and transmits the player’s choices.

For optical character recognition, a scanner first captures the printed page and converts it into a digital image. OCR software can then analyze that image and identify its characters, so option A is correct. A speaker produces audio, a projector displays images on a surface, and a mouse provides pointing input; none initially captures the whole paper document.

The correct answer is B, the barcode scanner. It is a specialised input device that uses light to read the pattern of bars or other coded marks printed on a product label and sends the decoded information to the computer or billing system. A webcam captures general images, a microphone captures sound, and a projector displays information, so none of those devices is designed specifically to read product codes.

The correct answer is C, a plotter. A plotter is an output device designed to produce large, accurate drawings, maps, engineering plans, and charts on paper. It is especially useful when precise lines and a large page size are required. A scanner captures paper content as input, a speaker produces sound, and a mouse provides control input, so none of them prints large drawings.

The correct answer is D, an Uninterruptible Power Supply, commonly called a UPS. It contains a battery and power-control circuitry that provide temporary electricity when the main supply fails. This short backup period allows a user to save work and shut the computer down safely. A scanner, printer, and speaker may use electricity, but they do not provide backup power to the computer.

The correct answer is C, application software. A word processor is created to help a user perform a specific task—in this case, creating, editing, formatting, and saving documents. Application software works with the operating system and hardware but is not itself a physical component. Hardware and the system unit are tangible parts, while an input unit is used to enter data rather than write documents.

The correct answer is A: input, processing, and output. First, the computer receives raw data through an input device or method. Next, the processor applies instructions and performs calculations or other operations. Finally, the system produces a result through an output device, such as a monitor or printer. The other sequences reverse or combine activities and do not describe the basic IPO cycle.

The governing concept is the CPU’s register storage. Registers are very small, extremely fast storage locations inside the processor that temporarily hold operands, instructions, addresses, or intermediate results during execution. Therefore option A is correct. A hard disk and pen drive are persistent secondary-storage devices, while printer memory belongs to a peripheral and is not the processor’s register set.

A network card, also called a network interface card, enables a computer to connect and communicate with a wired or wireless network. It sends and receives data through the network connection, allowing access to shared files, other computers, and internet services. Printing is done by a printer, sound recording by a microphone, and visual display by a monitor, so option B is the only suitable answer.

The computer case is the outer enclosure, or cabinet, that holds and protects important internal parts such as the motherboard, processor, memory, storage drive, and power supply. It also helps arrange these parts safely and may support airflow. A monitor displays information, a keyboard cover protects only a keyboard, and a mouse pad supports mouse movement; therefore option C is correct.

Hardware means the physical parts of a computer that can be seen and touched, such as the keyboard, monitor, processor, memory chips, and printer. Software is the set of programs and instructions that operates the hardware, while data is information processed by the computer. Instructions are commands, not the physical components themselves. Thus option A correctly describes touchable computer parts.

The Central Processing Unit, or CPU, executes program instructions and performs arithmetic and logical calculations. It coordinates many operations of the computer, which is why it is often called the brain of the computer. A keyboard and scanner send input, while a speaker produces sound output. Since only the CPU performs the central processing described, option C is correct.

A monitor is an output device that displays text, images, video, windows, and other visual results produced by a computer. It presents information on a screen so the user can see the result of processing. A keyboard, mouse, and microphone are input devices because they send text, selections, or sound into the computer. Therefore option D is the only correct answer.

A keyboard is the standard input device for typing letters, numbers, punctuation marks, and commands. Pressing its keys sends the selected characters or instructions to the computer. A mouse is mainly used for pointing, clicking, and selecting; a monitor displays results; and a printer produces paper output. Because typing requires key entry, option A is the correct answer.

A mouse is a pointing input device used to move the pointer and select items on a screen. A user can click an icon, file, button, or menu with the mouse, and a double-click can open many items. A printer produces paper output, a speaker produces sound, and a microphone captures sound, so none of those performs ordinary screen selection. Hence option B is correct.

A scanner is an input device that reads printed text, photographs, or drawings from paper and converts them into digital data. The resulting file can then be stored, edited, or shared on a computer. A printer performs the opposite direction by putting digital content onto paper, while a monitor displays information and a speaker produces sound. Therefore option C is correct.

A speaker is an output device that converts the computer’s electrical or digital audio signals into sound that a person can hear. Therefore, option A is correct. A microphone performs the opposite function by entering voice into the computer, while a scanner captures printed material and a webcam captures images or video. The governing concept is that output devices deliver processed information to the user.

A microphone is an input device that changes spoken words or other sound into electrical and then digital signals that a computer can record, store, or process. Thus, option B is correct. A speaker sends sound from the computer to the user, whereas a scanner reads printed material and a webcam captures visual input. The governing concept is that input devices transfer information into a computer.

A webcam is a visual input device that captures moving images and sends the video into a computer for recording, communication, or processing. Therefore, option C is correct. A mouse supplies pointer control, a speaker produces audio output, and a printer creates a paper copy of digital information. The governing concept is that cameras provide visual input, while output devices present or reproduce information for the user.

A projector receives presentation data from a computer or another source and enlarges the images, text, or video onto a wall or large screen. Hence, option D is correct. A scanner converts paper material into digital input, a keyboard enters text or commands, and a microphone enters sound. The governing concept is that a projector is an output device used to present visual information to an audience.

RAM, or Random Access Memory, temporarily holds the instructions and data currently needed by running programs. This fast working memory allows the processor to access active information quickly, so option A is correct. Its contents are generally lost when power is removed. ROM stores relatively permanent instructions, while a pen drive and DVD are removable long-term storage media.

The permanent or relatively fixed startup instructions required during booting are generally stored in ROM, so option B is correct. ROM is non-volatile memory, meaning its contents remain available when the computer is switched off. RAM is temporary working memory, cache holds frequently needed data for speed, and the clipboard temporarily holds copied items. These functions make the alternatives unsuitable.