Q1) Do electrons go first and only after they reached the other side the current appears? Or does the current appear first and it is the reason electrons start to move in the first place?
Q2) Is this the case for lightning too? If so, does it mean there is the current that goes from Earth to thunderclouds?
In: Physics
Contrary to the other responses, current does not cause the flow of electrons. Current IS the flow of electrons. It does not cause itself.
**Voltage** is what causes electrons to flow. Voltage induces current. (Hence the equation V = IR, voltage equals current times resistance.)
Voltage is when the two ends of a conductive “wire” attach to two substances with very different electric charges (potential, really). For instance, the negative terminal of a battery has a much more negative electric charge than the positive terminal of the battery. When you attach the two ends of a wire to the two terminals of a battery, the strong negative electric charge in the negative terminal will push on the electrons in the wire, and the strong positive charge in the positive terminal will pull on the electrons in the wire, nudging them down the wire towards the positive end. That movement is the current.
Electrons go “backwards” in a positive current because electrons are negatively charged, and the current is positive. It’s just nomenclature. It makes more sense to define a positive current as positive charges moving forward, because current can refer to the flow of positive charges as well. Thus, positive charges more forward in a positive current, and negative charges move backwards in a positive current.
(Edit: Like, consider if electrons had positive charge. Then they would be drawn towards the negative terminal of the battery and pushed away by the positive terminal. So they would flow the opposite direction if they had opposite charge. The direction positive charges will flow in a circuit is defined as the positive values of current.)
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