What is Voltage and current

Chapter 1.4 Voltage and current

Lessons In Electric Circuits Volume I – DC Book
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Summary of Contents

Lessons In Electric Circuits Volume I – DC Book

  • 14CHAPTER 1. BASIC CONCEPTS OF ELECTRICITY1.4Voltage and currentAs was previously mentioned, we need more than just a continuous path (circuit) before a con-tinuous flow of electrons will occur: we also need some means to push these electrons aroundthe circuit. Just like marbles in a tube or water in a pipe, it takes some kind of influencingforce to initiate flow. With electrons, this force is the same force at work in static electricity:the force produced by an imbalance of electric charge.If we take the examples of wax and wool which have been rubbed together, we find thatthe surplus of electrons in the wax (negative charge) and the deficit of electrons in the wool(positive charge) creates an imbalance of charge between them. This imbalance manifestsitself as an attractive force between the two objects:attractionWool clothWax- - -- ------- --------- ------------+ +++++++ +++++++ +++++++++++++++++ +++++ ++++++If a conductive wire is placed between the charged wax and wool, electrons will flow throughit, as some of the excess electrons in the wax rush through the wire to get back to the wool,filling the deficiency of electrons there:Wool clothWax- - ------ -----------+ +++++ +++++++++++++ +++++ ++++wire---electron flowThe imbalance of electrons between the atoms in the wax and the atoms in the wool createsa force between the two materials. With no path for electrons to flow from the wax to thewool, all this force can do is attract the two objects together. Now that a conductor bridges theinsulating gap, however, the force will provoke electrons to flow in a uniform direction throughthe wire, if only momentarily, until the charge in that area neutralizes and the force betweenthe wax and wool diminishes.The electric charge formed between these two materials by rubbing them together serves tostore a certain amount of energy. This energy is not unlike the energy stored in a high reservoirof water that has been pumped from a lower-level pond: