What are the physical layer device? Give the name and function feature of physical device?

Question

or if u guys know any website about it then post em please :) thanks

Answer 1

A physical layer device would be the actual medium such as the coax cable, UTP cable, Fiber and a network device such as a hub, not a switch ( Switches work at the datalink layer #2). Their function is to provide the actual physical link for communication

Answer 2

http://www.ethermanage.com/ethernet/100quickref/ch9qr_4.html
The next device in the block diagram is called the Physical Layer Device (PHY). This device performs the same general function as a transceiver in the 10-Mbps Ethernet system. It may be a set of integrated circuits inside the Ethernet port of a network device, therefore invisible to the user, or it may be a small box equipped with an MII cable, like the outboard transceiver and transceiver cable used in 10-Mbps Ethernet.