Recently when I was procrastinating, I have learned that an electric energy is not propagated via wires but through fields. Once a circuit is closed, a field is created and it carries the energy from a source to eg a light bulb. It proposed a question to me.
The question is, how does the current/source know that the circuit has been closed?
Let’s ask two similar questions, both assume ideal conditions.
1. we have a source and a switch on Earth and a light bulb on Mars. We close the circuit using the switch and the energy starts to be emitted from the source in an almost instant. After some time, once the field reaches the bulb, it starts to emit light.
2. we have the same situation, but the switch is moved to Mars. Will it take the same time for the bulb to emit light? How does the source know that the circuit has been closed and it can start to emit and electric field?
In: 0
The field is not always there, it required electrons to move.
The source doesn’t know a circuit is closed any more than a ball knows a hand is holding it up. The force to pull it down is always there until you let go.
Moving the switch changes nothing, as the electrons don’t physically need to move the full length. It bfhaves like marbles in a pipe filled to both ends. Push one in and the last one pops out. The marble didn’t move all the way but just displaced the one beside it.
Latest Answers