Physical media
Physical media refers to the physical materials that are used to store or transmit information in data communications. These physical media are generally physical objects made of materials such as copper or glass. They can be touched and felt, and have physical properties such as weight and color.[1] For a number of years, copper and glass were the only media used in computer networking.
This article is about physical medias as materials. For the physical media in the context of society and the media industry, see Media preservation.The term physical media can also be used to describe data storage media like records, cassettes, VHS, LaserDiscs, CDs, DVDs, and Blu-rays, especially when compared with modern streaming media or content that has been downloaded from the Internet onto a hard drive or other storage device as files.
Types of physical media[edit]
Copper wire[edit]
Copper wire is currently the most commonly used type of physical media due to the abundance of copper in the world, as well as its ability to conduct electrical power.[1] Copper is also one of the cheaper metals which makes it more feasible to use.[1]
Most copper wires used in data communications today have eight strands of copper, organized in unshielded twisted pairs, or UTP.[1] The wires are twisted around one another because it reduces electrical interference from outside sources. In addition to UTP, some wires use shielded twisted pairs (STP), which reduce electrical interference even further.[2] The way copper wires are twisted around one another also has an effect on data rates. Category 3 cable (Cat3), has three to four twists per foot and can support speeds of 10 Mbit/s.[1] Category 5 cable (Cat5) is newer and has three to four twists per inch, which results in a maximum data rate of 100 Mbit/s.[1] In addition, there are category 5e (Cat5e) cables which can support speeds of up to 1,000 Mbit/s, and more recently, category 6 cables (Cat6), which support data rates of up to 10,000 Mbit/s (i.e., 10 Gbit/s).[1]
On average, copper wire costs around $1 per foot.[1]
Debate on physical media[edit]
With technology constantly changing, there is a debate on whether physical media is still prudent and necessary to an increasingly wireless world.[4] Wireless and physical media may actually complement each other, and physical media will matter more, not less, in a society dominated by the wireless technology.[4] However, other opinions by people consider physical media a dead technology that will eventually disappear.[5]