Thomas Johann Seebeck
Encyclopedia
Thomas Johann Seebeck was a physicist
who in 1821 discovered the thermoelectric effect
.
Seebeck was born in Reval (today Tallinn
, Estonia
) to a wealthy Baltic German merchant family. He received a medical degree in 1802 from the University of Göttingen, but preferred to study physics. In 1821 he discovered the thermoelectric effect, where a junction of dissimilar metals produces an electric current when exposed to a temperature gradient. This is now called the Peltier–Seebeck effect and is the basis of thermocouple
s and thermopile
s.
s, with junctions at different temperatures would deflect a compass magnet
. Seebeck initially believed this was due to magnetism
induced by the temperature difference. However, it was quickly realized that it was an electrical current that is induced, which by Ampere's law
deflects the magnet. More specifically, the temperature difference, produces an electric potential (voltage
) which can drive an electric current in a closed circuit. Today, this effect is known as the Peltier–Seebeck effect.
The voltage produced is proportional to the temperature difference between the two junctions. The proportionality constant (a) is known as the Seebeck coefficient, and often referred to as the thermoelectric power or thermopower
. The Seebeck voltage does not depend on the distribution of temperature along the metals between the junctions. This effect is the physical basis for a thermocouple, which is used often for temperature measurement.
The voltage difference, V, produced across the terminals of an open circuit made from a pair of dissimilar metals, A and B, whose two junctions are held at different temperatures, is directly proportional to the difference between the hot and cold junction temperatures, Th − Tc.
The voltage or current produced across the junctions of two different metals is caused due to the diffusion of electrons from high electron density region to low electron density region as the density of electrons is different in different metals. Due to this the current flows in opposite direction.
If both the junctions are kept at same temperature,equal amount of electron diffuses at both the junctions. Therefore the current at both the junctions are equal and opposite and the net current is zero, and if both the junctions are kept at different temperature then diffusion at both the junctions are different and hence different amount of current is produced. Therefore the net current is not zero. This is known as the phenomena of thermoelectricity.
, Seebeck described the action of the spectrum of light on the chloride of silver. He observed that the exposed chemical would sometimes take on a pale version of the color of light that exposed it, and also reported the action of light for a considerable distance beyond the violet end of the spectrum. Seebeck also worked on the Theory of Colours
with Goethe
.
of potassium. In 1810, he observed the magnetic properties of nickel and cobalt. In 1818, Seebeck discovered the optical activity of the solutions of sugar.
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
who in 1821 discovered the thermoelectric effect
Thermoelectric effect
The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice-versa. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it, it creates a temperature difference...
.
Seebeck was born in Reval (today Tallinn
Tallinn
Tallinn is the capital and largest city of Estonia. It occupies an area of with a population of 414,940. It is situated on the northern coast of the country, on the banks of the Gulf of Finland, south of Helsinki, east of Stockholm and west of Saint Petersburg. Tallinn's Old Town is in the list...
, Estonia
Estonia
Estonia , officially the Republic of Estonia , is a state in the Baltic region of Northern Europe. It is bordered to the north by the Gulf of Finland, to the west by the Baltic Sea, to the south by Latvia , and to the east by Lake Peipsi and the Russian Federation . Across the Baltic Sea lies...
) to a wealthy Baltic German merchant family. He received a medical degree in 1802 from the University of Göttingen, but preferred to study physics. In 1821 he discovered the thermoelectric effect, where a junction of dissimilar metals produces an electric current when exposed to a temperature gradient. This is now called the Peltier–Seebeck effect and is the basis of thermocouple
Thermocouple
A thermocouple is a device consisting of two different conductors that produce a voltage proportional to a temperature difference between either end of the pair of conductors. Thermocouples are a widely used type of temperature sensor for measurement and control and can also be used to convert a...
s and thermopile
Thermopile
A thermopile is an electronic device that converts thermal energy into electrical energy. It is composed of several thermocouples connected usually in series or, less commonly, in parallel....
s.
Seebeck effect
In 1821 Thomas Johann Seebeck found that a circuit made from two dissimilar metalMetal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
s, with junctions at different temperatures would deflect a compass magnet
Magnet
A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets.A permanent magnet is an object...
. Seebeck initially believed this was due to magnetism
Magnetism
Magnetism is a property of materials that respond at an atomic or subatomic level to an applied magnetic field. Ferromagnetism is the strongest and most familiar type of magnetism. It is responsible for the behavior of permanent magnets, which produce their own persistent magnetic fields, as well...
induced by the temperature difference. However, it was quickly realized that it was an electrical current that is induced, which by Ampere's law
Ampère's law
In classical electromagnetism, Ampère's circuital law, discovered by André-Marie Ampère in 1826, relates the integrated magnetic field around a closed loop to the electric current passing through the loop...
deflects the magnet. More specifically, the temperature difference, produces an electric potential (voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
) which can drive an electric current in a closed circuit. Today, this effect is known as the Peltier–Seebeck effect.
The voltage produced is proportional to the temperature difference between the two junctions. The proportionality constant (a) is known as the Seebeck coefficient, and often referred to as the thermoelectric power or thermopower
Thermopower
The thermopower, or thermoelectric power of a material is a measure of the magnitude of an induced thermoelectric voltage in response to a temperature difference across that material...
. The Seebeck voltage does not depend on the distribution of temperature along the metals between the junctions. This effect is the physical basis for a thermocouple, which is used often for temperature measurement.
The voltage difference, V, produced across the terminals of an open circuit made from a pair of dissimilar metals, A and B, whose two junctions are held at different temperatures, is directly proportional to the difference between the hot and cold junction temperatures, Th − Tc.
The voltage or current produced across the junctions of two different metals is caused due to the diffusion of electrons from high electron density region to low electron density region as the density of electrons is different in different metals. Due to this the current flows in opposite direction.
If both the junctions are kept at same temperature,equal amount of electron diffuses at both the junctions. Therefore the current at both the junctions are equal and opposite and the net current is zero, and if both the junctions are kept at different temperature then diffusion at both the junctions are different and hence different amount of current is produced. Therefore the net current is not zero. This is known as the phenomena of thermoelectricity.
Precursors to color photography
In 1810, at JenaJena
Jena is a university city in central Germany on the river Saale. It has a population of approx. 103,000 and is the second largest city in the federal state of Thuringia, after Erfurt.-History:Jena was first mentioned in an 1182 document...
, Seebeck described the action of the spectrum of light on the chloride of silver. He observed that the exposed chemical would sometimes take on a pale version of the color of light that exposed it, and also reported the action of light for a considerable distance beyond the violet end of the spectrum. Seebeck also worked on the Theory of Colours
Theory of Colours
Theory of Colours is a work by Johann Wolfgang von Goethe about the poet's views on the nature of colours and how these are perceived by man, published in 1810...
with Goethe
Johann Wolfgang von Goethe
Johann Wolfgang von Goethe was a German writer, pictorial artist, biologist, theoretical physicist, and polymath. He is considered the supreme genius of modern German literature. His works span the fields of poetry, drama, prose, philosophy, and science. His Faust has been called the greatest long...
.
Other achievements
In 1808, Seebeck was first to produce and describe the amalgamAmalgam (chemistry)
An amalgam is a substance formed by the reaction of mercury with another metal. Almost all metals can form amalgams with mercury, notable exceptions being iron and platinum. Silver-mercury amalgams are important in dentistry, and gold-mercury amalgam is used in the extraction of gold from ore.The...
of potassium. In 1810, he observed the magnetic properties of nickel and cobalt. In 1818, Seebeck discovered the optical activity of the solutions of sugar.