The Physical Layer is the first layer of the Open Systems Interconnection (OSI) Model. The Physical Layer deals with bit-level transmission between different devices and supports electrical or mechanical interfaces connecting to the physical medium for synchronized communication.
This layer plays with most of the network’s physical connections - wireless transmission, cabling, cabling standards and types, connectors and types, network interface cards, and more - as per network requirements. However, the physical layer does not deal with the actual physical medium (like copper, fiber).
Source: Physical Layer