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The physical layer creates the electrical, optical or microwave signal that represents a bit in each frame that are sent on the media one at a time. These signals are passed to the Data Link layer as a complete frame by the physical layer which first restores the signals back to their bit representations. The three basic forms of network media on which data is represented are copper cable, fibre optics and wireless Organizations need the following technology for physical layer standards: Physical and electrical properties of the media Mechanical properties of the connectors Encoding Definition of control information signals NICs, interfaces and connectors, cable materials, and cable designs are all specified in standards associated with the Physical layer. The three fundamental functions of the Physical layer are: The physical components Data encoding Signalling Frames The Physical layer encodes the bits into the signals for a particular medium and also distinguishes where one frame ends and the next frame begins so that the devices on the media would know when the frame is fully received. The destination device would only receive a string of signals and would not be able to properly reconstruct the frame. The Physical layer may add its own signals to indicate the beginning and end of the frame in certain technologies otherwise the Data Link layer does it. The delivery of frames across the local media requires the following Physical layer elements: The physical media and associated connectors A representation of bits on the media Encoding of data and control information Transmitter and receiver circuitry on the network devices Unshielded Twisted Pair (UTP) in *Ethernet LANs*: UTP cabling consists of four pairs of colour-coded wires that have been twisted together and then enclosed in a flexible plastic covering. The twisting cancels unwanted signals. Coaxial Cable: Coaxial cable...