Discussion of the Question 11/99
OHM'S LAWThe question was:
Nowadays high school and university students use voltmeters and ammeters to demonstrate Ohm's law. These devices were not available in Ohm's time! (Moreover, these devices rely on laws (including Ohm's law) not known at the time.) How did Ohm do it? Suggest experiments (using only equipment available in 1826, or similar present-day equipment) showing that:
(a) "voltage" is proportional to "current";
(b) for fixed "voltage", the "current" is proportional to the cross-sectional area of the wire and inversely proportional to its length.
(2/2000) Ahmet Uysal (e-mail uysal@scientist.com) sent us the following e-mail:
There are lots of interesting points in your question. Lets have a look:
* In 1820 Oersted showed that a current can affect a magnet. It was possible that to make a galvanometer in 1826. And Ohm produced his tools by himself.
* More important point is a voltmeter has same principle with ammeter. And both of them stand on Ohm's law. How can you prove a law by using itself?
So, this is very interesting point. But I think you have to change the way of your question. It is far from the reality. You can look at these documents to get more real information:
1- Electromagnetics: History, Theory and Applications ; Robert Selliot.
2- Intellectual Mastery of Nature: Physicists from Ohm to Einstein.
3- American Journal of Physics, 1963, sh.544
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