8. Fiber optic cable. Signaling.

Fiber optic cables are made of glass or plastic. They have a very high bandwidth, which enables them to carry very large amounts of data.

Fiber optic can be either glass or plastic with a diameter about the same as a human hair that carry digital information at very high speeds over long distances. Since they use light instead of electricity, electrical interference does not affect the signal. They are also used in medical imaging, medical treatment and mechanical engineering inspection

There are two forms of fiber optic cable: multimode and single mode.

Single Mode. Produces single straight path for light. Glass core = 9 microns, glass cladding 125 microns diameter, has polymeric coating. Core is small, dispersion is less, suited for the long distance applications, uses lasers as the light source.

Multimode. Allows multiple paths for light. Glass core = 50-62,5 microns, glass cladding 125 microns diameter, has just coating. Core is larger than in single mode, allows greater dispersion and therefore loss of signal.

Signalling

Optical fiber can be used as a medium for telecommunication and computer networking because it is flexible and can be bundled as cables. It is especially advantageous for long-distance communications, because light propagates through the fiber with little attenuation compared to electrical cables.

For short distance application, such as a network in an office building, fiber-optic cabling can save space in cable ducts.

9) Wireless networks. Network adapter card.

Wireless network refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications networks and enterprise (business) installations avoid the costly process of introducing cables into a building, or as a connection between various equipment locations. This implementation takes place at the physical level (layer) of the OSI model network structure. A wireless local-area network (LAN) uses radio waves to connect devices such as laptops to the Internet and to your business network and its applications. When you connect a laptop to a WiFi hotspot at a cafe, hotel, airport lounge, or other public place, you're connecting to that business's wireless network.

Network adapter cards allow computers to connect to networks and to access the Internet via routers and access points. Network adapter cards may also be referred to as network interface cards or NICs. Network adapter cards can be wired (or Ethernet) or wireless. A network adapter card acts as an interface beween the computer and the network cable. The card is Inserted in an expansion slot of each computer of the network. The function of the network card is to manage the flow of network information to and from the computer in which it resides. Before the data is sent over the network the network adapter card converts it into a form that can travel over a network cable. This is accomplished through the translation of the computer's digital signals into electrical and optical signals that can travel on the network cable. For example, token ring adapters want to receive a toen transmitting and release the token after transmitting.