# 1911 Encyclopædia Britannica/Ohm, Georg Simon

**OHM, GEORG SIMON** (1787-1854), German physicist, was
born at Erlangen on the 16th of March 1787, and was educated
at the university there. He became professor of mathematics
in the Jesuits' college at Cologne in 1817 and in the polytechnic
school of Nuremberg in 1833, and in 1852 professor of experimental
physics in the university of Munich, where he died on
the 17th of July 1854. His writings were numerous, but, with
one important exception, not of the first order. The exception
is his pamphlet published in Berlin in 1827, with the
title *Die galvanische Kette mathematisch bearbeitet*. This work,
the germs of which had appeared in the two preceding
years in the journals of Schweigger and Poggendorff, has exerted
most important influence on the whole development of the
theory and applications of current electricity, and Ohm's name
has been incorporated in the terminology of electrical science.
Nowadays "Ohm's Law," as it is called, in which all that is
most valuable in the pamphlet is summarized, is as universally
known as anything in physics. The equation for the propagation
of electricity formed on Ohm's principles is identical with
that of J. B. J. Fourier for the propagation of heat; and if, in
Fourier's solution of any problem of heat-conduction, we change
the word "temperature" to "potential" and write "electric
current" instead of "flux of heat," we have the solution of
a corresponding problem of electric conduction. The basis
of Fourier's work was his clear conception and definition of
conductivity. But this involves an assumption, undoubtedly
true for small temperature-gradients, but still an assumption,
viz. that, all else being the same, the flux of heat is strictly
proportional to the gradient of temperature. An exactly similar
assumption is made in the statement of Ohm's law, *i.e.* that,
other things being alike, the strength of the current is at each
point proportional to the gradient of potential. It happens, however,
that with our modern methods it is much more easy to test
the accuracy of the assumption in the case of electricity than
in that of heat; and it has accordingly been shown by J. Clerk
Maxwell and George Chrystal that Ohm's law is true, within
the limits of experimental error, even when the currents are so
powerful as almost to fuse the conducting wire.