Written by: Ahmed Abdel Salam
Many believe that electricity travels through wires at the speed of light, but scientific reality reveals greater complexity, as the speed of current transmission is linked to three different movements within conductors, each with its own nature and speed.
Random Motion of Electrons
The first motion is represented by the individual speed of electrons moving within the atomic structure of the wire in random paths, constantly colliding with atoms and changing direction. The speed of this random motion can reach millions of miles per hour, but it does not represent a steady electric current because the electrons do not move in one direction, and their collisions contribute to generating heat within the wire.
Slow Drift Velocity
When an electric field is applied to a conductor, as happens when connecting a battery, a force arises that pushes the electrons to move in a specific direction, resulting in what is known as "drift velocity," which is the net speed of electron movement under the influence of the electric field. Surprisingly, this speed is extremely slow and may not exceed a few feet per hour, depending on the physical conditions of the conductor and the intensity of the current.
Why Do Devices Work Immediately Upon Turning Them On?
If electrons move this slowly, why does a lamp light up immediately upon pressing the switch? The answer lies in the fact that energy transmission does not depend on the movement of a single electron from the source to the device, but rather on the propagation of the electromagnetic field within the circuit. This can be compared to a water hose that is already full; when the tap is opened, water rushes out from the other end quickly because the water molecules push each other along the length of the hose.
The Electromagnetic Signal Approaches the Speed of Light
The third and most relevant movement to the speed of device operation is the propagation speed of the electromagnetic signal. When the electric circuit is closed, the electromagnetic field propagates along the conductor at a very high speed approaching the speed of light, affecting the electrons located throughout the circuit, so their organized movement begins almost synchronously. Estimates indicate that the speed of electrical signal propagation may exceed 600 million miles per hour, while remaining slower than the speed of light in a vacuum.
Distinguishing Between Signal Speed and Internet Speed
This distinction extends to the world of communications and digital networks, as the high speed of electromagnetic signal transmission does not mean that digital data travels at the same rate under all circumstances. The data transfer rate also depends on the efficiency of electronic devices and routers and their ability to process and send data packets.
