IP work with all type of media that bring the data at lower layers of the OSI Model. Therefore, IP packets travel as electrical signals over copper cable, as optical signals over fiber, or wirelessly as radio signals.
The OSI data link layer is responsible for taking an IP packet and preparing it for transmission over the communications medium. The transmission of the IP packet is not limited to any particular medium. So the IP packet travels over any available transmission media.
The PDU maximum size considered on each medium. This characteristic called MTU (Maximum Transmission Unit). The MTU is the part of the control communication between the data link layer and the network layer. The data link layer passes the MTU value upwards to the network layer. The network layer then determines how large packets can be. When a packet is forwarding from one medium to another, sometimes, an intermediate device, split up a packet with a smaller MTU. This process is packet fragmentation.