# What happens when switch is open [duplicate]

In a simple circuit, composed only of a lamp, a generator and a switch that connects the generator to the lamp. What happens with electric current when the switch is open? Electrons turn around? They go in the air scattered in infinity (lol)? I would like to know (I am a beginner).

## marked as duplicate by pipe, Edgar Brown, Dwayne Reid, laptop2d, Kevin ReidFeb 25 at 17:47

• Are you looking for a simplified analogy or a comprehensive physical model? – Eugene Sh. Feb 22 at 15:00
• What circuit? Electrons / currents go in loops. If there is no loop (like when a switch is open) then no current will flow. The electrons do not "go back" they stay where they are (that's a simplified view, ignoring quantum effects etc.). Also: as a beginner: why do you care so much about what the electrons do? You can perfectly understand circuits by just thinking about current / no current. No need to consider electrons. – Bimpelrekkie Feb 22 at 15:00
• All the voltage appears across that (open) switch, thus no voltage is available in the wiring to push electrons along. – analogsystemsrf Feb 22 at 15:06
• What happens to the water in the pipe when you turn off the faucet? Does it turn around and go back to the pump? Does it scatter in the air? – hobbs Feb 22 at 15:23

The current arcs across the open contacts in the switch for a bit (this is what electrons moving through the air is like lightning) and there is a infinitesmal amount of electrons that continues to flow since everything has a resistance (except for maybe a vacuum like in vacuum tubes which function differently). Since electrons are discrete particles though, at some point zero electrons can move across the air gap.

The arcing can be thought of the inertia behind the current, like trying to stop a train from moving; It doesn't stop right away. It's due to inductance so if the lamp were an inductor or coil with lots of inductance, the arc would last a lot longer. Transmission stations can have enormous arcs that last for a several seconds.

Also note the electrons actually move very slowly as they "flow" in the wire. The wave of electrons bouncing against each other is what moves near the speed of light. An electron isn't moving back and forth from one end of the wire to the other 50 or 60 times per second in 50/60Hz AC, but the wave is. That might help you clarify things in your mind. It's like how sound moves much much faster than wind.

Simple answer: for all practical purposes, the electrons stop moving.

We could talk about quantum tunneling through the energy barrier of the air gap but I don't think you care about that.

Current must flow in a closed loop. For current to flow in one direction through the switch there must be an identical current flowing in the opposite direction through another wire, back to the generator. If you break the loop then both currents stop.

• ignore the edits. I meant to edit my post. – DKNguyen Feb 22 at 15:34