2009/03/10

March 10 in Russian history. Stoletov's research of photoelectric effect

1888

(26 February Old Style)

The experiment set by Alexander Stoletov is finally successful. The photoelectric effect was first observed in 1839 by Becquerel, but its discovery is usually attributed to Heinrich Hertz. Stoletov, though, was the first who deduced the laws and patterns of this effect.

Here's a little biography of Stoletov taken from Russia-InfoCentre:

Born: August 10, 1839

Deceased: May 27, 1896

Eminent Russian physicist, Alexander Stoletov, was born to the family of a merchant in 1839. Alexander’s father owned a grocery shop and his mother, a well-educated woman, did her best to teach her children Russian language and arithmetic before they started attending a secondary school. Alexander was four when he learned to read and he spent days reading, since his health wasn’t very good.

In 1849 Alexander entered the gymnasium in Vladimir. He graduated it seven years after with a diploma of honours and gold medal for outstanding achievements in learning. Same year Alexander Stoletov was enrolled to the faculty of physics and mathematics of Moscow State University and received educational scholarship from the state.

In 1860 Alexander finished the university and passed master’s examination. However, master thesis defense had to be postponed, because Alexander Stoletov went to Europe for new knowledge. He spent three years in Berlin, Heidelberg and Gottingen, studying physics, and fascinated physicists with his talent. (He studied at Gustav Kirchhoff, who called Stoletov "his most gifted student" DM)

First scientific research Alexander Stoletov performed abroad. Young scientist found out that dielectric properties of water had no effect on electromagnetic interaction of conductors. In 1865 Stoletov returned to Russia and soon got a position of a teacher of mathematical physics and physical geography in Moscow State University. Physicist read brilliant lectures and prepared his master thesis, "The General Problem of Electrostatics and Its Reduction to the Simplest Form". Young scientist solved this problem and defended his master thesis in 1869. Following years were spent in effort to create his own physical laboratory – Moscow State University had no experimental facilities, and scientists had to go abroad to perform research. In 1871 Alexander Stoletov started working on his doctor dissertation and studied magnetic properties of iron. Creating a theory of how electric machines worked was an important task, since there was no such science as “electro-techniques”. Stoletov again went to Germany, where he discovered some important patterns in the magnetism of iron.

In 1872 Alexander Stoletov successfully defended his doctor dissertation, and the following year brought him a position of professor in Moscow University. Same year his physical laboratory finally opened – Russian scientists didn’t need to go abroad to perform experiments anymore. The physicist read popular lectures, wrote popular scientific papers and supervised a physical society. After defense of doctor dissertation Alexander Stoletov became a world-known scientist – he visited opening ceremony of physical laboratory in Cambridge in 1874, and represented Russian science at I World Congress of Electricity in Paris in 1881, where he reported on proportion factors between electrostatic and electromagnetic units of measure. Stoletov suggested using Ohm for electric resistance. In 1888 Alexander Stoletov started studies of photo effect, which was discovered by Hertz the year before. Elegant experiments resulted in a discovery of the law linking critical pressure, electromotive force of a battery and distance between the electrode and the net. Later this constant was named after him.

In 1893, three Academy members recommended Stoletov for becoming a member of the Academy of Sciences. However, the President of the Academy, Great Prince Konstantin, refused to sign necessary papers explaining himself with the “unbearable temper of Alexander Stoletov”. Such decision was a hard blow for the physicist, and many scientists sympathized with him due to that unfair situation. Health of the great scientist was weak since his early childhood, and in May 1896 Alexander Stoletov died of pneumonia.

Some other important works of Stoletov include:

  • On the Kohlrausch's measurement of the mercury unit of electric resistance;
  • Sur une méthode pour déterminer le rapport des unités électromagnétiques et électrostatiques;
  • On the electricity of juxtaposition;
  • On the critical state of bodies (4 articles);
  • Actino-electric research;
  • Ether and electricity;
  • Essay on the development of our knowledge of gases;
  • Introduction into acoustics and optics.

Some Stoletov's achievements:

  • Stoletov was the first to show that with the increase of the magnetic field the magnetic susceptibility of iron grows, but then begins to decrease.
  • He built the curve of the magnetic permeability of ferromagnetics, known as the Stoletov's curve.
  • Developed two new methods of measurement of magnetic properties of various materials.
  • He calculated the the proportion between electrodynamic and electrostatic units, producing a value very close to the speed of light.
  • Studied the outer photoelectric effect, discovered by Hertz.
  • Built the first solar cell based on the outer photoelectric effect and estimated the response time of the photoelectric current.
  • Discovered the direct proportionality of the intensity of light and the current caused by it (Stoletov's law)
  • Discovered the decrease of the solar cell's sensitivity with time (fatigue of solar cells).
  • Developed quantitative methods of the study of the photoelectric effect.
  • Discovered the Stoletov's constant (defines the ratio between the intensity of the electric current and the gas pressure under the maximum current).

2 comments:

Anonymous said...

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http://history-of-wars.ru/

Dmitri Minaev said...

Thank you!