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Chapter 1 - The Fundamentals
This chapter gives you an easy-to-understand explanation of conductivity. Therefore, it is free of strictly scientific discussion or professional content, to help you become familiar with the basics that will be helpful in using a conductivity meter. Anyway, please read on with ease of mind.
Alessandro Volta was a physicist born in Italy in 1745. He became known in 1800 as the inventor of the first electric battery. Unlike the friction batteries known up to that time, the Volta battery provided continuous electric current, and was one of the great inventions of the century. This achievement by Volta paved the way for the likes of Georg Ohm, the German physicist who measured the conductivity of metals, and in 1827 discovered the now-famous Ohm's law.
Michael Faraday was born in 1791, the son of an English blacksmith. At age 13, he became a bookbinder's apprentice, which gave him access to many books. In 1833, he became an assistant to Professor Davies of the Royal Research Laboratory. He did prominent work in the fields of chemistry and physics, and in 1833, he conceived the law of electrolysis, and he envisioned ion as made of corpuscles that conveyed electricity in solution.
The conductivity of electrolytes was energetically measured by Friedrich Kohlrausch of Germany between 1869 and 1880. It is said that he started measuring conductivity as a means of obtaining ionic product. The Kohlrausch bridge, which he invented at that time for the purpose of measuring conductivity, is still well known today.
A. Volta |
(Italy) |
1745-1827 |
G. Ohm |
(Germany) |
1787-1854 |
M. Faraday |
(England) |
1791-1867 |
F. Kohlrausch |
(Germany) |
1840-1910 |
Do you remember Ohm's law, which you learned about in school as one of the basic principles of electricity? In our daily lives, however, we don't need to use Ohm's law. In fact, most of us have our own electrical resistance--we simply walk away when the conversation turns to technobabble about electricity. Since a detailed discussion of electricity would merely cloud the issue, we will try to stick to the basics and make a long story short--and a lot easier to understand.
The above formula describes Ohm's law.
The electricity we use at home in Japan has electromotive force of 100 volts, flashlight batteries 1.5 volts. This is called voltage.
When you connect a little bulb to a battery, the bulb glows. It glows because electric current flows through the bulb. But the flow of current is hindered by what is called resistance, and the larger the resistance, the harder it is for the current to flow.
Try to apply Ohm's law to a river. The difference in height between the head of the river and its mouth is the voltage, and the volume of water that flows is the current. The length and width of the river and the obstacles in the river are the resistance.
It means that the greater the difference in the heights of the water flowing in the river, the shorter and wider the river and the fewer obstacles in the river, the greater the volume of water that can flow.
To refresh your memory, think of the following question:
Question: How much current (in amperes) flows when a little bulb of 3 ohms at the time it is turned on is connected to a 1.5-Volt battery?
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