A Discussion of the Life of Heinrich Friedrich Emil Lenz - jtooker.com
A Discussion of the Life of Heinrich Friedrich Emil Lenz - jtooker.com
A Discussion of the Life of Heinrich Friedrich Emil Lenz - jtooker.com
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Abstract<br />
A <strong>Discussion</strong> <strong>of</strong> <strong>the</strong> <strong>Life</strong> <strong>of</strong> <strong>Heinrich</strong> <strong>Friedrich</strong> <strong>Emil</strong> <strong>Lenz</strong><br />
J. B. Tooker<br />
Electrical Engineering 306<br />
December 5, 2007<br />
<strong>Heinrich</strong> <strong>Friedrich</strong> <strong>Emil</strong> <strong>Lenz</strong> was a precise and devoted scientist pioneering <strong>the</strong> field <strong>of</strong><br />
electromagnetics while leading <strong>the</strong> way in recording and preparing his experiments, now known as<br />
scientific method. The detailed and <strong>com</strong>plete methods <strong>of</strong> his work have given researchers <strong>the</strong> world<br />
over a standard to live up to. The record <strong>of</strong> his personal life, on <strong>the</strong> o<strong>the</strong>r hand, did not get as much<br />
<strong>of</strong> his attention. <strong>Lenz</strong> is best regarded as a precise investigator ra<strong>the</strong>r <strong>the</strong>n a gifted innovator. His<br />
dutiful research led him to <strong>the</strong> Law that bears his name.
Throughout <strong>the</strong> course <strong>of</strong> human history, people have sought to describe <strong>the</strong> mysterious<br />
world around <strong>the</strong>m. The effects and implementations <strong>of</strong> electromagnetics is a fairly late but<br />
-1-<br />
Tooker<br />
explosive study. Although first „discovered‟ before 500 BC, most research in this field did not begin<br />
until <strong>the</strong> 17 th century (Whittaker; Peters). <strong>Heinrich</strong> <strong>Lenz</strong> began his research as many <strong>of</strong> <strong>the</strong><br />
fundamental, but separate, laws governing electromagnetism were being established. His work<br />
related <strong>the</strong> laws <strong>of</strong> electromagnetism with <strong>the</strong>mselves and o<strong>the</strong>r physical laws, though not to <strong>the</strong><br />
extent or prestige <strong>of</strong> J. C. Maxwell.<br />
<strong>Heinrich</strong> <strong>Friedrich</strong> <strong>Emil</strong> <strong>Lenz</strong> was born are raised in <strong>the</strong> town <strong>of</strong> Dorpat, although it is now<br />
known as Tartu, in Estonia. He studied at <strong>the</strong> University <strong>of</strong> Tartu from 1820 to 1823 in <strong>the</strong> area <strong>of</strong><br />
<strong>the</strong>ology, but soon he switched <strong>the</strong> study <strong>of</strong> physics (“DGPT - <strong>Heinrich</strong> <strong>Lenz</strong>”). After graduation,<br />
<strong>Lenz</strong> ac<strong>com</strong>panied Otto von Kotzebue on a worldwide voyage as geophysical scientist. His work<br />
during this voyage focused on climatic conditions as he “made extremely accurate measurements <strong>of</strong><br />
<strong>the</strong> salinity, temperature, and specific gravity <strong>of</strong> sea water,” (“<strong>Heinrich</strong> F. E. <strong>Lenz</strong> Biography”).<br />
Right from <strong>the</strong> start it is seen how well <strong>Lenz</strong> kept notes on his findings and <strong>the</strong> accuracy <strong>of</strong> his<br />
measurements. This talent will contribute greatly to his later discoveries (“<strong>Heinrich</strong> F. E. <strong>Lenz</strong><br />
Biography”).<br />
Though a biological record <strong>of</strong> <strong>Lenz</strong>‟s life is not available, it is seen from his publications that<br />
<strong>Lenz</strong> was an energetic and intellectually gifted man. Scientists are not apt to leaving records <strong>of</strong> <strong>the</strong>ir<br />
lives, while even <strong>the</strong> least well-known literary author “takes occasion to leave a sufficient record <strong>of</strong><br />
his life to show what <strong>the</strong> manner <strong>of</strong> <strong>the</strong> man was,” (Stine 64). It can be assumed that <strong>Lenz</strong> was a<br />
clever and able man, just as it can be assumed <strong>of</strong> most scientists, when knowledge <strong>of</strong> <strong>the</strong>ir life is<br />
in<strong>com</strong>plete. The titles <strong>of</strong> <strong>Lenz</strong>‟s first publications give <strong>the</strong> first indication <strong>of</strong> <strong>Lenz</strong>‟s character. In<br />
chronological order <strong>the</strong>y are: 1<br />
� “On <strong>the</strong> Temperature and <strong>the</strong> Salt-Content <strong>of</strong> <strong>the</strong> Water <strong>of</strong> <strong>the</strong> Ocean at Different<br />
Depths”<br />
� “Report on a Journey to Baku”<br />
� “Physical Observations Made during a Voyage around <strong>the</strong> World with Captain Von<br />
Kotzebue, in <strong>the</strong> Years, 1823-6”<br />
� “On <strong>the</strong> Comparative Quantity <strong>of</strong> Salt Contained in <strong>the</strong> Waters <strong>of</strong> <strong>the</strong> Ocean”<br />
� “On <strong>the</strong> Influence upon <strong>the</strong> Movements <strong>of</strong> <strong>the</strong> Beam <strong>of</strong> a Balance, Due to Bodies at<br />
Different Temperatures in its Neighborhood”<br />
� “On <strong>the</strong> Variations in Height which <strong>the</strong> Surface <strong>of</strong> <strong>the</strong> Caspian Sea Has Suffered to April<br />
<strong>of</strong> <strong>the</strong> Year 1830”<br />
The seventh published paper – <strong>the</strong> first <strong>of</strong> great significance – entitled “On <strong>the</strong> Laws which<br />
Govern <strong>the</strong> Action <strong>of</strong> a Magnet upon a Spiral, when it is suddenly Approached toward, or<br />
1 Note: <strong>the</strong>se titles are English translations (Stine 66-67).
Withdrawn from it; as <strong>the</strong> most Advantageous Method for Constructing Spirals for Magneto-<br />
-2-<br />
Tooker<br />
Electrical Purposes,” is an indication <strong>of</strong> <strong>Lenz</strong>‟s pr<strong>of</strong>essional transition to electromagnetic research in<br />
1832. Up until <strong>the</strong> 1820‟s, electric and magnetic phenomena were considered separate subjects. In<br />
1827 Ampère published his electromagnetic <strong>the</strong>ory based on Oersted‟s observations (Peters). <strong>Lenz</strong>‟s<br />
seventh paper shows <strong>the</strong> true nature <strong>of</strong> <strong>Lenz</strong> as a scientist. The fruits <strong>of</strong> this paper were derived<br />
from <strong>the</strong> reproduction <strong>of</strong> Faraday‟s published experiments, thus making <strong>the</strong> identification <strong>of</strong> <strong>Lenz</strong>‟s<br />
original initiatives a challenge. Both Henry and Faraday published papers in <strong>the</strong> same area earlier<br />
that year, October and February, respectfully (Stine 68).<br />
While <strong>the</strong> originality <strong>of</strong> <strong>Lenz</strong>‟s early papers may be ambiguous, what is clear is how<br />
accurately and <strong>com</strong>pletely <strong>Lenz</strong> carried out his experiments, <strong>of</strong>ten to a finer precision <strong>the</strong>n <strong>the</strong><br />
original scientist. In addition to Faraday‟s experiments, <strong>Lenz</strong> measured <strong>the</strong> forces and magnetic<br />
actions caused by a spiral abruptly drawn away and brought towards a magnet (Stine 70). This<br />
precise, quantitative research is what separated <strong>Lenz</strong> from his contemporaries who focused on more<br />
qualitative research.<br />
Today, quantitative findings are <strong>the</strong> basis <strong>of</strong> modern research, and science places less<br />
emphasis on <strong>the</strong> imaginative and <strong>the</strong> qualitative innovation approach (Stine 70-71). The use <strong>of</strong><br />
„scientific method‟ shows this. Continuing this type <strong>of</strong> research, <strong>Lenz</strong> outlined measurable<br />
parameters that could affect <strong>the</strong>se “electromotive spirals” before digging blindly into this new field<br />
<strong>of</strong> research. These characteristics were:<br />
1. The number <strong>of</strong> convolutions in <strong>the</strong> spiral<br />
2. The Breadth,<br />
3. Thickness,<br />
4. And substance <strong>of</strong> <strong>the</strong> convolutions (Stine 71).<br />
To validate an experiment, it must be reproducible by o<strong>the</strong>rs. <strong>Lenz</strong> takes great care in<br />
describing <strong>the</strong> instruments he used, so that o<strong>the</strong>rs may know how accurate his findings were. At this<br />
time in history, one was not able to go to an electronics shop and simply purchase an accurate<br />
multimeter. His galvanometer was “constructed with Nobili‟s double or astatic needle; and was<br />
wound with 74 turns <strong>of</strong> wire, 0.635mm in diameter. Describing o<strong>the</strong>r details <strong>of</strong> <strong>the</strong> apparatus, <strong>the</strong><br />
paper states, „I wound <strong>the</strong> electromotive wire about a s<strong>of</strong>t iron cylinder, which served as an<br />
armature, and was filed smooth and flat at those places, where it was laid on <strong>the</strong> poles <strong>of</strong> <strong>the</strong> magnet.<br />
As <strong>the</strong> removal <strong>of</strong> <strong>the</strong> armature can be performed in a more certain, prompt and uniform manner<br />
than <strong>the</strong> placing <strong>of</strong> it on <strong>the</strong> poles, I have, in all my following experiments, given <strong>the</strong> results which<br />
were obtained by pulling away <strong>the</strong> armature, or by <strong>the</strong> sudden removal <strong>of</strong> magnetism from <strong>the</strong><br />
iron,‟” (Stine 71-72). <strong>Lenz</strong> takes this care in every step <strong>of</strong> his reports to assure o<strong>the</strong>rs that his<br />
experiments are true to <strong>the</strong>ir claims.<br />
<strong>Lenz</strong> proceeded to test <strong>the</strong>se variables he had prepared using <strong>the</strong> recent laws in<br />
electromagnetism. Not only did he use <strong>the</strong>se laws but also he fully understood <strong>the</strong>m, having
discovered some <strong>of</strong> <strong>the</strong>se laws himself before learning <strong>of</strong> Ohm‟s work (Ohm 613). In addition to<br />
his understanding <strong>of</strong> <strong>the</strong> significance <strong>of</strong> <strong>the</strong>se laws, he also “knew how to <strong>com</strong>bine <strong>the</strong>m<br />
quantitatively,” (Stine 73).<br />
The results <strong>of</strong> this study show: “The electromotive power, which a magnet produces in a<br />
-3-<br />
Tooker<br />
spiral with convolutions <strong>of</strong> equal magnitude, and with a wire <strong>of</strong> equal thickness and like substance, is<br />
directly proportional to <strong>the</strong> number <strong>of</strong> its convolutions.” Defined in C. G. S. units (Centimeter,<br />
Gram, Seconds) as opposed to M. K. S. units (Meter, Kilogram, Second, known as SI after 1960)<br />
(Stine 74; Rowlett):<br />
Continuing his detailed description, in <strong>the</strong> second experiment <strong>of</strong> this paper, <strong>Lenz</strong> describes<br />
his apparatus: “I wound <strong>the</strong> copper wire in six convolutions around a wooden wheel 28 inches in<br />
diameter, and placed <strong>the</strong> wheel on <strong>the</strong> iron cylinder. After having <strong>com</strong>pleted <strong>the</strong> experiment, I<br />
wound six convolutions <strong>of</strong> <strong>the</strong> same wire about <strong>the</strong> same iron cylinder.” He found <strong>the</strong> acting<br />
electromotive forces were almost identical leading him to conclude, “The electromotive power<br />
which <strong>the</strong> magnetism produces in <strong>the</strong> surrounding spiral, is <strong>the</strong> same for every magnitude <strong>of</strong> <strong>the</strong><br />
convolutions” (Stine 75).<br />
Testing different diameters <strong>of</strong> wire, each 33 feet in length and wound ten times, he noted <strong>the</strong><br />
resistance <strong>of</strong> each wire was negligible, despite <strong>the</strong>ir different diameters. The electromotive force was<br />
constant for each <strong>of</strong> <strong>the</strong>se three tests. He generalizes, “The electromotive power produced in <strong>the</strong><br />
spirals by <strong>the</strong> magnet, remains <strong>the</strong> same for every thickness <strong>of</strong> <strong>the</strong> wire or is independent <strong>of</strong> it,”<br />
(Stine 75-76).<br />
The next <strong>of</strong> <strong>Lenz</strong>‟s discoveries states, “<strong>the</strong> electromotive power, which <strong>the</strong> magnet produces<br />
in spirals <strong>of</strong> wire <strong>of</strong> different substances, under like conditions, is <strong>the</strong> same for all substances,” (Stine<br />
76). Modern research <strong>of</strong>ten fails to give <strong>Lenz</strong> accreditation for this simple principle, despite its<br />
importance and usefulness. “Ferro-magnetic winding, whose permeability is greater than unity, such<br />
materials affect <strong>the</strong> value <strong>of</strong> <strong>the</strong> factor dN and mask <strong>the</strong> final result,” (Stine 76-77).<br />
Reflecting on <strong>the</strong> results <strong>of</strong> previous magnetic research around his geographical area, <strong>Lenz</strong><br />
states, “Nobili and Antinori, in <strong>the</strong>ir first paper on <strong>the</strong> electrical phenomena produced by <strong>the</strong><br />
magnet, have already determined <strong>the</strong> order in which four different metals are adapted to produce <strong>the</strong><br />
electric current from magnetism. They arrange <strong>the</strong>se in <strong>the</strong> following order: copper, iron, antimony,<br />
and bismuth.”<br />
“It is particularly striking that <strong>the</strong> order is <strong>the</strong> same as that which <strong>the</strong>se metals occupy, also in<br />
reference to <strong>the</strong>ir capacity <strong>of</strong> conducting electricity: and <strong>the</strong> idea suddenly occurred to me, whe<strong>the</strong>r<br />
<strong>the</strong> electromotive power <strong>of</strong> <strong>the</strong> spirals did not remain <strong>the</strong> same in all metals; and whe<strong>the</strong>r <strong>the</strong><br />
stronger current in <strong>the</strong> one metal did not arise from its being a better conductor <strong>of</strong> electricity,”
(Stine 77). <strong>Lenz</strong> proceeded to test copper, iron, platinum and brass in pairs – connected <strong>the</strong>m in<br />
-4-<br />
Tooker<br />
series – under <strong>the</strong> same physical dimensions. No change was found in <strong>the</strong> resistance <strong>of</strong> <strong>the</strong> circuits.<br />
Continuing with his rigorous reporting, he mentions several o<strong>the</strong>r factors he took into<br />
account and minimized. All <strong>of</strong> <strong>the</strong>se tests took Thermo-electric precautions as Seebeck had made<br />
discoveries in this area ten years before electromotive forces derived from magnetism were<br />
discovered. The connection <strong>of</strong> wires was also addressed: he found a less than point-two percent<br />
difference between twisting wires toge<strong>the</strong>r ten times and using pliers to force and flatten <strong>the</strong> wires<br />
toge<strong>the</strong>r. Perhaps one aspect that he did not realize was <strong>the</strong> difference between static galvanometric<br />
readings and impulsive deflections, causing error in his current measurements.<br />
Comparing <strong>Lenz</strong> with his contemporaries at this point <strong>of</strong> his life shows Faraday and Henry<br />
as pioneers in this new field, with <strong>Lenz</strong> refining and generalizing <strong>the</strong>ir discoveries. Though “Faraday<br />
showed preeminent genius in seeking after <strong>the</strong> causes <strong>of</strong> <strong>the</strong> new phenomena, and developing <strong>the</strong><br />
useful working hypo<strong>the</strong>sis <strong>of</strong> tubes <strong>of</strong> force. Both Henry and Faraday neglected to attempt any<br />
ma<strong>the</strong>matical formulation and deduction from <strong>the</strong>ir experiments,” (Stine 84-85). <strong>Lenz</strong> is <strong>the</strong> more<br />
modern scientist, precise and analytical, methodically examining every aspect <strong>of</strong> an experiment.<br />
Looking only at his early work, one would not be alone in wondering if <strong>Lenz</strong> did not possessed true<br />
genius, but was purely a judicious researcher. Later publications give insight to a better conceptual<br />
understanding that is lacking in his early reports.<br />
For a period <strong>of</strong> time after <strong>Lenz</strong> finished <strong>the</strong>se electromagnetic experiments, and before<br />
starting his more famous ones, he studied electrical resistance and conductivity in metals. Though<br />
electrical in practice, <strong>the</strong>se studies incorporate much <strong>of</strong> his earlier work. He continued to find and<br />
explain <strong>the</strong> generalizations he discovered, while continuing to apply scientific method. Of <strong>the</strong>se<br />
studies, perhaps <strong>the</strong> most intriguing ones dealt with <strong>the</strong> resistance <strong>of</strong> a material due to temperature.<br />
On June 7, 1833 his paper entitled, “On <strong>the</strong> Conductivity <strong>of</strong> Metals at Different Temperatures for<br />
Electricity,” was read before <strong>the</strong> Academy <strong>of</strong> St. Petersburg (Sting 88). At this time formulas had<br />
not been derived that explained his hypo<strong>the</strong>sis. After struggling with his current formulas and initial<br />
experiments, he determined that <strong>the</strong> internal resistance <strong>of</strong> his battery pushed <strong>the</strong> uncertainty factor<br />
<strong>of</strong> <strong>the</strong>se experiments past <strong>the</strong> effects that changing temperature would produce.<br />
At this point <strong>Lenz</strong>‟s ingenuity starts to shine. Faced with a dead end in using a non-ideal battery,<br />
he turned to <strong>the</strong> electromotive spirals to measure <strong>the</strong> currents needed to explain <strong>the</strong> temperature<br />
dependence. He was now able to determine <strong>the</strong> exact resistance <strong>of</strong> each material, and measure <strong>the</strong>se<br />
magnitudes very accurately. From <strong>the</strong>se studies, <strong>Lenz</strong> developed this relationship:<br />
This formula has been improved upon until it became what it is today:
-5-<br />
Tooker<br />
Matthiessen is <strong>the</strong> one usually credited with this relationship, while textbooks hardly mention <strong>Lenz</strong>,<br />
especially English books (Stine 90, 91).<br />
As a standard unit had not been created yet, <strong>Lenz</strong> defined his own unit <strong>of</strong> resistance. He<br />
defined his resistances as <strong>com</strong>pared to a unit length <strong>of</strong> copper wire at a certain diameter. In an 1834<br />
paper he disproves Ritchie‟s observations <strong>of</strong> conductivity, using simple algebraic expressions<br />
showing <strong>the</strong> relationships <strong>of</strong> voltage, current and resistance, similar to <strong>the</strong> works <strong>of</strong> Ohm and<br />
Fechner. The expression he derived is shown below, where J is current, E is voltage, and W is <strong>the</strong><br />
resistance (Stine 94-96).<br />
When connecting a real circuit, thus taking into account <strong>the</strong> wires, this expression is derived<br />
for <strong>the</strong> current, where l/c is resistance in terms <strong>of</strong> <strong>the</strong> unit length <strong>of</strong> copper:<br />
Solving for W yields,<br />
a resistance, standardized to a unit length <strong>of</strong> copper. Having a setup that would not change under<br />
different loads, <strong>Lenz</strong> was <strong>the</strong>n able to insert resistances, R, into his system, which would yield <strong>the</strong>ir<br />
respective currents, J‟‟.<br />
This crude and almost roundabout way <strong>of</strong> accurately measuring resistances yielded results that<br />
agreed quit well with those found later by scientists with better and more modern instruments. He<br />
tested and determined <strong>the</strong> conductivity <strong>of</strong> silver, copper, gold, iron, tin, lead, platinum as well as<br />
many o<strong>the</strong>r conductors. Using Ohms Law (not called such at <strong>the</strong> time) as an axiom, <strong>Lenz</strong> states,<br />
“The conductibility <strong>of</strong> wires <strong>of</strong> <strong>the</strong> same substance, is inversely as <strong>the</strong>ir length and directly as <strong>the</strong>ir<br />
cross-section” (Stine 97). And he acknowledges <strong>the</strong> use <strong>of</strong> electrodynamic current to find <strong>the</strong>se<br />
resistances as sufficiently accurate, while deducing that internal resistances <strong>of</strong> <strong>the</strong> batteries and<br />
circuits used by o<strong>the</strong>r researchers caused <strong>the</strong>ir failures and inability to determine this relationship for<br />
<strong>the</strong>mselves. <strong>Lenz</strong> did not discover here (but would later) <strong>the</strong> impedance effects <strong>of</strong> materials in an<br />
AC system, though his experiments (luckily) did not depend on any <strong>of</strong> <strong>the</strong>se impeditive effects.<br />
<strong>Lenz</strong> is most famous for a generalization, bearing <strong>the</strong> name <strong>Lenz</strong>‟s Law. First announced in<br />
his paper, “On <strong>the</strong> Direction <strong>of</strong> Galvanic Currents Which Are Excited through Electrodynamic<br />
Induction,” read before <strong>the</strong> Academy at St. Petersburg on November 29, 1833 (Stine 102). Faraday
stated two laws, though <strong>Lenz</strong> argued that <strong>the</strong>y were describing <strong>the</strong> same phenomenon, Faraday<br />
stated:<br />
-6-<br />
Tooker<br />
I) “Between parallel conductors, one <strong>of</strong> which carries a current, an opposing current is induced<br />
upon approach toward, and a current similarly directed upon withdrawal from <strong>the</strong> first<br />
conductor.”<br />
II) “When a conductor is moved near a magnet, <strong>the</strong> direction <strong>of</strong> <strong>the</strong> induced current depends<br />
upon <strong>the</strong> manner <strong>of</strong> cutting <strong>the</strong> magnetic curves,” (Stine 103).<br />
<strong>Lenz</strong>‟s Law was derived from a literal interpretation <strong>of</strong> Ampère‟s hypo<strong>the</strong>sis in an attempt to more<br />
accurately state what Faraday had tried to say.<br />
In attacking Faraday‟s conclusion, <strong>Lenz</strong> gives several instances where Faraday‟s two laws<br />
would be incorrect. His first situation places a conductor perpendicular to a second conductor in<br />
which a current circulates. According to Faraday, no current would be induced in this conductor,<br />
when moved parallel with itself and, in its plane <strong>of</strong> movement, parallel with <strong>the</strong> inducing conductor<br />
(Stine 107).<br />
After studying Faraday‟s papers, as well as Nobili‟s <strong>com</strong>ments on <strong>the</strong>m, he began to seek a<br />
<strong>com</strong>mon phenomenon that could describe electrodynamic phenomena. After verifying his<br />
expectations <strong>of</strong> Faraday‟s experiments, <strong>Lenz</strong> states (translated into English), “The electrodynamic<br />
action <strong>of</strong> an induced current opposes equally <strong>the</strong> mechanical action inducing it,” (Stine 111). <strong>Lenz</strong>‟s<br />
Law itself is a specific example <strong>of</strong> Conservation <strong>of</strong> Energy, not developed until 14 years later (Stine<br />
112).<br />
A simple example, that shows <strong>Lenz</strong>‟s law, is to take a coil <strong>of</strong> wire and drop it through a<br />
magnetic field. When <strong>the</strong> coil is open-circuited (no current will flow in <strong>the</strong> wires) it will fall quickly<br />
due to gravity. When <strong>the</strong> coil is short-circuited, it will appear to resist <strong>the</strong> force <strong>of</strong> gravity due to <strong>the</strong><br />
fact that energy is required to induce <strong>the</strong> current that is now allowed to flow through <strong>the</strong> coil. Here<br />
it can be seen that <strong>Lenz</strong>‟s law is a specific example <strong>of</strong> <strong>the</strong> conservation <strong>of</strong> energy. See Figure 1. A<br />
video demonstrating this is available at http://msdaif.googlepages.<strong>com</strong>/demo_lenz (Daif).<br />
In 1845 Neumann published this expression derived from <strong>Lenz</strong>‟s Law:<br />
“Where E.Ds is <strong>the</strong> electromotive force induced in <strong>the</strong> element Ds; v is <strong>the</strong> velocity with which Ds is<br />
moved; C denotes <strong>the</strong> magnitude <strong>of</strong> <strong>the</strong> resolved action <strong>of</strong> <strong>the</strong> induction upon Ds when unit current<br />
is considered to be flowing in this element. The magnitude <strong>of</strong> ε is independent <strong>of</strong> <strong>the</strong> activity <strong>of</strong> <strong>the</strong><br />
induced conductor” under linear induction, which is constant, but is a function <strong>of</strong> time (Stine 113-<br />
114).<br />
Ano<strong>the</strong>r phrasing <strong>of</strong> <strong>Lenz</strong>‟s Law from his paper reads, “To each phenomenon <strong>of</strong> movement<br />
by electromagnetism, <strong>the</strong>re must correspond an electrodynamic distribution. Consequently it is only<br />
necessary to produce motion through o<strong>the</strong>r means in order to induce a current in <strong>the</strong> moveable
-7-<br />
Tooker<br />
conductor, which shall be opposed in direction to that so produced in <strong>the</strong> induced conductor <strong>of</strong> <strong>the</strong><br />
electromagnetic tests,” (Stine 116). Though fully understanding this law in <strong>the</strong> realm <strong>of</strong><br />
electrodynamics, <strong>Lenz</strong> almost hints at, but does not discuss, its fur<strong>the</strong>r application in terms <strong>of</strong> its<br />
greatest significance: conservation <strong>of</strong> energy (Stine 115-116).<br />
One quickly notices how <strong>com</strong>pletely <strong>Lenz</strong> tests this law. Unlike <strong>the</strong> work <strong>of</strong> Faraday,<br />
Ampère and many o<strong>the</strong>rs, <strong>Lenz</strong> thoroughly tests every aspect surrounding his findings. He<br />
<strong>com</strong>prehensively and logically planned his experiments to be <strong>com</strong>plete and test every variable that<br />
could be accounted for, and he was successful. In this paper, <strong>Lenz</strong> separately <strong>com</strong>pares <strong>the</strong> similar<br />
conclusions <strong>of</strong> Faraday and Ampère, and o<strong>the</strong>rs in relation to his law as well as his view <strong>of</strong> <strong>the</strong><br />
matter.<br />
<strong>Lenz</strong> was immersed in <strong>the</strong> beginning <strong>of</strong> <strong>the</strong> study <strong>of</strong> electromagnetism for <strong>the</strong> 30 years after<br />
1833. He, Faraday and Henry were <strong>the</strong> early pioneers <strong>of</strong> this field. Much <strong>of</strong> <strong>the</strong> later work in this<br />
scientific area is in <strong>the</strong> application <strong>of</strong> <strong>the</strong> laws found in this short, accelerated research. In<br />
<strong>com</strong>menting on <strong>Lenz</strong>‟s contributions to science, W. M. Stine elaborates, “Nei<strong>the</strong>r in his<br />
contributions nor investigations can he be called brilliant; he, perhaps, did little, if anything, which<br />
would not subsequently have been done: yet all his work was <strong>of</strong> that solid and enduring character,<br />
which forms <strong>the</strong> foundation <strong>of</strong> all science. His methods were painstaking and exhaustive: he<br />
verified, extended and formulated,” (Stine 129-130).<br />
<strong>Lenz</strong>‟s later works continued to show his dutiful and meticulous manner <strong>of</strong> experimentation.<br />
After Joule released his law for <strong>the</strong> heating effect <strong>of</strong> an electrical current, “<strong>Lenz</strong> verified and<br />
extended <strong>the</strong> investigations in a precise and remarkable manner,” (Stine 132). He eliminated <strong>the</strong><br />
cooling effects <strong>of</strong> air by cooling his apparatus far below room temperature, and <strong>the</strong>n he proceeded<br />
to test many different metals, followed by taking into account <strong>the</strong> specific heat <strong>of</strong> <strong>the</strong> wires he was<br />
using. He also sought to maximize <strong>the</strong> output <strong>of</strong> electromotive forces from magneto-electric<br />
generators. In <strong>the</strong>se investigations, he charted his data as a waveform using a method that is largely<br />
used today.<br />
His life came to an anti-dramatic end as he suffered a stroke on February 10, 1865 while in<br />
Rome for medical reasons. He died at <strong>the</strong> age <strong>of</strong> 61 (“<strong>Heinrich</strong> F. E. <strong>Lenz</strong> Biography”).<br />
<strong>Lenz</strong>‟s scrupulous research methods and recognition <strong>of</strong> <strong>the</strong> implications <strong>of</strong> his electromotive<br />
coils make him stand out as one <strong>of</strong> <strong>the</strong> great electromagnetic scientists. Despite <strong>the</strong> lack <strong>of</strong><br />
originality in his work, <strong>Lenz</strong> was able to draw conclusions that his colleagues overlooked, especially<br />
when it came to quantifying observable – and as <strong>Lenz</strong> showed – measurable phenomena.
Figure 1<br />
-8-<br />
Tooker
Works Cited<br />
-<br />
MLA format<br />
Daif, Mustafa. EduMation - <strong>Lenz</strong>'s Law. 2007 Mar. 2007. 30 Nov. 2007<br />
.<br />
-9-<br />
Tooker<br />
DGPT - <strong>Heinrich</strong> <strong>Lenz</strong>. 2003. 14 Nov. 2007<br />
.<br />
<strong>Heinrich</strong> <strong>Friedrich</strong> <strong>Emil</strong> <strong>Lenz</strong> Biography. 17 Nov. 2007 .<br />
Ohm, G. S. Die galvanische Kette ma<strong>the</strong>matisch bearbeitet. Berlin, 1827.<br />
Peters, Richard Alan II. "A Brief Outline <strong>of</strong> <strong>the</strong> History <strong>of</strong> Electromagnetism." 2000.<br />
Rowlett, Russ. Units: CGS and MKS. 26 Oct 2003. 4 Dec 2007<br />
.<br />
Stine, Wilbur Morris. H. F. E. <strong>Lenz</strong> to Electromagnetism. Philadelphia: The Acorn Press, 1923.<br />
Note: this is <strong>the</strong> main source for this paper, as well as <strong>the</strong> cover photograph.<br />
Whittaker, E. T. A History <strong>of</strong> <strong>the</strong> Theories <strong>of</strong> Ae<strong>the</strong>r and Electricity. New York: AIP Press, 1987.