Media and propagation of Signals

The actual process of carrying a signal from point to point is called propagation.

Copper, aluminum, tin or nickel wire are used to propagate electricity.

Erbium-doped glass fibers, or plastic strands are used to propagate light.

The air itself is used to propagate laser beams, radio waves or microwave.

The copper, aluminum, nickel, tin, glass fibers, plastic and the air are all referred to as media (or the medium of transmission). Our string propagates the movement of our hand to the doorknob. The time it takes to propagate a signal through a device or piece of media is called propagation delay or latency.