Why is the Physical Link at Layer 1 of the OSI?

Cellular towers relay information

Copper wiring transmits the electrical signal

Data is checked to make sure it is complete

The sender is identified

Data is checked to make sure it is complete

Layer 1, provides physical connections for transmission and performs the electrical encoding of data. This layer transforms bits to electrical signals.

The lowest, or first, layer of the OSI model. Protocols in the physical layer generate and detect signals so as to transmit and receive data over a network medium. These protocols also set the data transmission rate and monitor data error rates, but do not provide error correction.