Understanding Mechanical and Electromagnetic Waves, Telecommunications, and Computer Peripherals
Mechanical and Electromagnetic Waves
Mechanical waves require a material medium to propagate. For example, water waves are produced by the impact of an object. Electromagnetic waves can propagate through a vacuum and material means. In 1887, the German physicist Heinrich Hertz was the first to produce and detect them.
Electromagnetic Spectrum
The electromagnetic spectrum is the set of electromagnetic waves of all possible wavelengths.
Telecommunications
Electric Telegraph
The electric telegraph used long or short electrical impulses transmitted by cable to a receiver, represented as dots and dashes. Samuel Morse developed the Morse code system of dots and dashes.
Radiotelegraphy
Radiotelegraphy involves transmission via computer terminals connected to telephone networks.
Telephone
A telephone consists of a base, a microphone, a headset or speakerphone, a keypad, and a buzzer.
Landlines
In landlines, the headphone and microphone are connected by a cable to the base from where the telephone connection originates.
Wireless Models
In wireless models, the headphone and microphone are connected via radio waves to a base at a relatively short distance.
Mobile Telephone
A mobile telephone is a radio transmitter and receiver in the microwave band. Signals are transported via cable or radio antennas from microwave and satellite.
Computer Peripherals
Bidirectional Peripherals
Examples of bidirectional peripherals include modems, touch screens, and multifunction printers.
Input Peripherals
Input peripherals receive information that is processed in a central processing unit to obtain results that are output using output peripherals. A motherboard contains the microprocessor (an integrated circuit that contains all elements of the central processing unit, executes instructions, performs arithmetic and logic operations, controls the machine, and exchanges data), a chipset, BIOS, ROM, connectors, and expansion cards.
Common Input Peripherals
- Keyboard: The most used peripheral to enter data.
- Mouse: Speeds up work in a graphical environment.
- Microphone: Records sounds.
- Joysticks, gamepads, and steering wheels: Facilitate gaming.
- Digital camcorders: Capture images in digital format.
- Barcode readers and digitizing pens.
Output Peripherals
Monitor
A monitor reports information through images. Screen sizes can be 14, 15, 17, or 21 inches.
- Pixels: Luminous points into which the screen is divided.
- Number of colors: Affects the quality of the image.
- Adjusting the image brightness and contrast is important.
Printer
A printer transfers image and text documents onto a sheet.
- Resolution: Measured in dots per inch (dpi).
- Print speed: Measured in pages per minute (ppm) or characters per second (cps).
Cables
- Braided cable: Consists of eight colored threads covered by a plastic cover.
- Coaxial cable: Central conductor thread covered with a plastic insulator and an external metallic mesh armor.
- Fiber optic: Uses pulses of light to transmit data.
Computer Networks
LANs (Local Area Networks)
Local Area Networks (LANs) are generally private. Common topologies include linear, ring, and star.
MANs (Metropolitan Area Networks)
Metropolitan Area Networks (MANs) cover small metropolitan areas.
WANs (Wide Area Networks)
Wide Area Networks (WANs) connect cities, countries, or continents.