Input and output devices (3)
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1.
Describe three different types of input devices used with a computer and state the specific purpose of each.
Here are three different types of input devices and their purposes:
- Keyboard: The keyboard is primarily used for entering text and characters into a computer system. It allows users to create documents, code, and input commands.
- Mouse: The mouse is a pointing device used to control a cursor on the screen. It's used for selecting items, navigating menus, and interacting with graphical user interfaces (GUIs).
- Microphone: A microphone is used to input audio signals into a computer. This can be used for recording voice notes, participating in video calls, or creating audio content.
2.
Explain the difference between a vector monitor and a raster monitor. Include a description of how each type displays images.
The key difference between vector and raster monitors lies in how they display images. A raster monitor displays images by scanning the screen line by line, creating a grid of pixels. Each pixel is illuminated to produce a picture. This is the most common type of monitor used today. A vector monitor, on the other hand, uses mathematical equations to define lines, curves, and shapes. It then draws these shapes directly on the screen. This results in sharper, more detailed images, especially for graphics and text, as the image is not limited by the pixel grid. Vector monitors are less common now due to the advancements in raster technology.
3.
A student is designing a system to automatically water a plant. The system should only water the plant if the soil is dry. Identify two different types of sensors that could be used to achieve this and explain, for each sensor, how it works and why it is appropriate for this task.
Two suitable sensors for this task are:
- Soil Moisture Sensor: This sensor works by measuring the volumetric water content of the soil. It typically uses a resistor or capacitive sensor that changes its electrical resistance or capacitance depending on the amount of moisture present. Higher moisture content leads to lower resistance/higher capacitance. This is appropriate because it directly measures the condition of the soil – whether it is dry or not. A low reading indicates dry soil, triggering the watering system.
- Temperature Sensor: While not a direct measure of soil moisture, a temperature sensor can be used in conjunction with a soil moisture sensor. Soil temperature can provide an indirect indication of dryness. Dry soil tends to be cooler than moist soil. The temperature sensor works by measuring the electrical resistance or voltage change caused by temperature variations. This is appropriate as it can help to avoid watering when the soil is cool (e.g., after a recent rain) and potentially prevent root rot. The system could be programmed to only water if the soil moisture is below a certain threshold *and* the soil temperature is above a certain threshold.