Probably at high school you have been told that current is a flow of electrons w

Question

Probably at high school you have been told that current is a flow of electrons within a conductor. Lets say you have a circuit that runs from point A (your locatin) to point b (240miles away). Once this circuit is connected to a power supply current is recorded. The question is this: once the circuit is closed and current is recorded will an electron originally located at point A travel to Point B and then back to Point A ? In general in case of electrical current within conductors do electrons physically move AND travel along the wire for long distances ? Please explain your reasoning without the use of mathematics

Explanation / Answer

In general electrons do travel in the conductors but the velocity of the electrons is limited by many factors such as potential difference between the ends of the conductor, resistance offered by the conductor, area of cross section of the conductor. Also the the electons trace a highly random path(like zig-zag) to reach from one point to another. But there is a net displacement of the electron in a given time interval. This net displcement allows us to calculate the velocity of the electrons and is called as drift velocity of electrons, denoted as Vd. Basic calculations and even experimental results establish that the drift velocity of electrons accounts to a few centimetres per second.

This clearly establishes that time required for an electron to travel for such large distances is very high. But the current is recorded in as soon as the power supply is switched on because of the transmission of electric intensity in the conductor with the speed of light. Electric intensity is the property of a material that depends on its shape, resistance and potential difference. But the speed at which it is transmited is maximum possible speed for anything such as light itself. So, the power supply is recorded even though the electron at the souce may never physically reach the destination.

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