Stoletov Alexander

Alexander Stoletov, Russian physicist, founder of electrical engineering, and professor in Moscow University, was born on10 August 1839.

Contribution to science:

Magnetism (1871–1872)

• 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.
• Built the curve of the magnetic permeability of ferromagnetics, known as the Stoletov curve.
• Developed two new methods for measuring magnetic properties of various materials.

Photoelectric effect (1888–1891)

• Studied the outer photoelectric effect, discovered by Hertz in 1887. Published the results in six works.
• Developed quantitative methods for the study of the photoelectric effect.
• Discovered the direct proportionality between the intensity of light and the corresponding photo induced current (Stoletov's law)
• Discovered the Stoletov constant which defines the ratio between the intensity of the electric current and the gas pressure under the maximum current.
• Built the first solar cell based on the outer photoelectric effect and estimated the response time of the photoelectric current.
• Discovered the decrease of the solar cell's sensitivity with time (fatigue of solar cells).

Other

• Calculated the proportion between electrodynamic and electrostatic units, producing a value very close to the speed of light.

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