Question

It is known that the drift velocity of electrons is only a few $mm/sec$ for a current of a few amperes. then how is it possible that a current is established almost instantaneously when a circuit is closed? for example, a bulb glows as soon as the connection is switched on. Explain.

Answer 1

Conductors

1. Free electrons abound in the conductor.
2. When the voltage is turned on, an electric field is formed at the speed of light throughout the conductor.
3. Every free-electron acquires drag velocity immediately, resulting in instant current.

Working of electrons

1. The electrons are given a "push" when we flip on the switch, and the effect of that push is conveyed down the wire.
2. There hasn't been a single electron that has moved from the switch to the light to turn it on.
3. Assume we have a tube (cylinder) filled with water and held in a gravity-free environment. Water will not spill out if there is no gravity, as is clear.
4. When we add a single drop of water to one end, another drop will emerge from the other.
5. The same is the case with electrons in a wire. It is filled with electrons. when one electron enters from one end then one electron will leave from the other end, although the absolute velocity of electrons is in $mm/sec$.

Analyzing

1. This is conceivable because an electric field is created in the circuit practically instantly after it is closed.
2. Every location in the circuit experiences a local electron drift as a result of this. Individual electrons do not have to migrate from one end of the conductor to the other to establish a current.
3. Due to the impact of the electric field, each free electron in the conductor accelerates until it collides with a positive ion of the metal and loses its drift speed.
4. The electrons go through a continual cycle of collisions and drift speed loss until they attain an average drift speed.