Friedrich Kohlrausch (physicist) facts for kids
Quick facts for kids
Friedrich Kohlrausch
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Friedrich Wilhelm Georg Kohlrausch (1840–1910)
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| Born | 14 October 1840 Rinteln
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| Died | 17 January 1910 (aged 69) |
| Nationality | German |
| Alma mater | University of Erlangen University of Göttingen |
| Known for | Work on electrolytes Conductometry Kohlrausch bridge |
| Scientific career | |
| Fields | Physicist |
| Institutions | University of Frankfurt/Main University of Göttingen ETH Zurich Darmstadt University University of Würzburg Strasbourg University Humboldt University |
| Doctoral advisor | Wilhelm Eduard Weber |
| Doctoral students | Walther Nernst Erasmus Kittler |
| Other notable students | Svante Arrhenius |
| Notes | |
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He was the son of Rudolf Kohlrausch, the grandson of Friedrich Kohlrausch, and the nephew of Otto Kohlrausch.
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Friedrich Wilhelm Georg Kohlrausch (born October 14, 1840 – died January 17, 1910) was a German scientist. He was a physicist who studied how well different materials could conduct electricity. He focused especially on liquids called electrolytes.
Kohlrausch also looked into things like how stretchy materials are (called elasticity). He studied how heat affects materials (thermoelasticity) and how heat moves through them (thermal conduction). He was very good at making super accurate measurements of magnetic and electrical forces.
Today, many people see Friedrich Kohlrausch as one of the most important physicists who did experiments. His early work helped to expand the way we measure electricity and magnetism. This built on the ideas of other famous scientists like Carl Friedrich Gauss and Wilhelm Weber.
Contents
About Friedrich Kohlrausch
Early Life and Education
Friedrich Wilhelm Georg Kohlrausch was born in Rinteln, Germany, on October 14, 1840. His father was Rudolf Kohlrausch, who was also a physicist.
Friedrich studied physics at the Erlangen and Göttingen universities. He earned his doctorate degree from Göttingen.
Teaching Career
After working for two years as a lecturer in Frankfurt, Kohlrausch became a professor of physics. This was at the University of Göttingen from 1866 to 1870.
In 1870, Kohlrausch moved to Switzerland to teach at ETH Zurich. A year later, he returned to Germany. He became a professor at the Darmstadt University of Technology.
In 1875, he accepted a job at the University of Würzburg in southern Germany. There, he did many experiments on how much electricity different substances could conduct. He also studied the conductivity of electrolytes. From 1888, he taught and researched at Strasbourg University.
He was offered a professorship at the Humboldt University in Berlin in 1894 but turned it down. However, he did become a professor there starting in 1900. In 1902, he was chosen as a member of the Royal Swedish Academy of Sciences.
Kohlrausch's Scientific Work
Studying Electrolytes
Kohlrausch was a very important researcher in the field of electrochemistry. This is the study of how electricity and chemical reactions are connected.
One of his most important discoveries was the law of independent migration of ions. This law explains how charged particles (called ions) move in a solution. His experiments helped other famous scientists like Svante Arrhenius learn about ions.
Kohlrausch's work helped connect "measuring physics" with the ideas of the Ionists. This meant that his careful measurements provided a lot of proof for their theories.
How Electrolytes Conduct Electricity
In 1874, Kohlrausch showed that an electrolyte has a specific amount of electrical resistance. This amount stays the same. By watching how conductivity changed when a solution was made weaker (diluted), he could figure out how fast ions moved.
He used alternating current (AC) in his experiments. This was important because it stopped unwanted chemical reactions from happening. For example, it prevented gases like hydrogen or oxygen from forming. This allowed him to get very accurate results.
From 1875 to 1879, he studied many solutions of salts, acids, and other materials. His hard work led to the law of the independent migration of ions. This law states that each type of ion has its own specific ability to conduct electricity. This is true no matter what other ions are in the solution.
Kohlrausch also showed that for weak electrolytes (those that don't fully break apart), the more diluted a solution is, the better it conducts electricity. This is because more ions break apart and become free to move.
New Measuring Tools and Methods
In 1895, Kohlrausch became the President of the Physikalisch-Technische Reichsanstalt (PTR). This was a very important German institute for physics and technology. He held this position until 1905.
At the PTR, he focused on experiments and building new tools. He created new ways to measure how well electrolytes conduct electricity. He also finished setting up the PTR, which was a big job. He put in place clear rules and work schedules for the institute.
Under Kohlrausch's leadership, the PTR created many important standards for measurements. These standards were used not only in Germany but also around the world.
Kohlrausch worked hard to make sure the laboratories had the best working conditions. He wanted to protect them from outside disturbances. For example, he fought for six years against a streetcar line being built near the PTR. He worried it would affect their sensitive measurements.
Before the streetcar started running, the institute developed a special torsion magnetometer. This device was not affected by disturbing electromagnetic fields. This meant that precise electrical and magnetic work could continue.
Over the years, Kohlrausch added experiments that helped both physical chemistry and electrical technology. He made precision measuring tools better. He also developed many new ways to measure things in almost all areas of physics known at that time. These included a device to measure how much light reflects (reflectivity meter) and different types of magnetometers.
The Kohlrausch bridge, which he invented to measure conductivity, is still well-known today. Kohlrausch understood how important both basic science and applied technology were. He laid the groundwork for scientific knowledge that helped industry grow. The PTR created standardized precision instruments for universities and factories. It also helped set uniform electrical units for Germany and played a big role in their international use.
Kohlrausch was involved in measuring electrical, magnetic, and electrochemical things for almost 50 years. In 1905, he retired from his job as President of the PTR.
Friedrich Kohlrausch passed away in Marburg on January 17, 1910, at the age of 69.
His Writings
While at the University of Göttingen, Kohlrausch wrote down his practical experiments. This led to his book Leitfaden der praktischen Physik (Guidelines to Practical Physics). It was published in 1870 and was the first book of its kind in Germany.
The book described experiments, how to set them up, and measuring techniques. It also included tables of physical quantities. It was published many times and translated into English. It became the standard book for physical laboratory methods and measurements.
Even today, the textbook Praktische Physik (Practical Physics) is a standard book for physicists and engineers in Germany. This is because it gives detailed descriptions of measuring methods. These methods are used in many areas of physics and technology.
Kohlrausch also wrote Ueber den absoluten Leitungswiderstand des Quecksilbers (On the electrical resistance of mercury, 1888). He also wrote many papers for scientific journals like the Annalen der Physik und Chemie.
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Friedrich Wilhelm Georg Kohlrausch (1840–1910)
