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4: Batteries, Resistors and Ohm's Law

Last updated

Mar 5, 2022
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- 3.10: A Geophysical Example
- 4.1: Introduction

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4.1: Introduction
An electric cell consists of two different metals, or carbon and a metal, called the poles, immersed or dipped into a liquid or some sort of a wet, conducting paste, known as the electrolyte, and, because of some chemical reaction between the two poles and the electrolyte, there exists a small potential difference (typically of the order of one or two volts) between the poles.
4.2: Resistance and Ohm's Law
The conventional direction of the flow of electricity is the direction in which positive charges are moving. That is to say, electricity flows from the positive electrode towards the negative electrode. The positive ions, then, are moving in the same direction as the conventional direction of flow of electricity, and the negative ions are moving in the opposite direction.
4.3: Resistance and Temperature
4.4: Resistors in Series
4.5: Conductors in Parallel
4.6: Dissipation of Energy
When current flows through a resistor, electricity is falling through a potential difference. When a coulomb drops through a volt, it loses potential energy 1 joule. This energy is dissipated as heat.
4.7: Electromotive Force and Internal Resistance
4.8: Power Delivered to an External Resistance
4.9: Potential Divider
A potential divider can be used to supply a variable voltage to an external circuit (where is called a rheostat) or it may be used to compare potential differences, in which case it is called a potentiometer.
4.10: Ammeters and Voltmeters
4.11: Wheatstone Bridge
The Wheatstone bridge can be used to compare the value of two resistances – or, if the unknown resistance is compared with a resistance whose value is known, it can be used to measure an unknown resistance.
4.12: Delta-Star Transform
4.13: Kirchhoff’s Rules
4.14: Tortures for the Brain
I don’t know if any of the examples in this section have any practical applications, but they are excellent ways for torturing students, or for whiling away rainy Sunday afternoons.
4.15: Solutions, Answers or Hints to 4.14
4.16: Attenuators

Thumbnail: Basic Wheatstone bridge. (CC BY-SA 4.0 International; Daraceleste via Wikipedia)

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