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2.  André-Marie Ampère
 From Wikipedia, the free encyclopedia

André-Marie AmpèreBorn20 January 1775
Lyon, Kingdom of FranceDied10 June 1836 (aged 61)
Marseille, Kingdom of
FranceNationalityFrenchFieldsPhysicsInstitutionsÉcole
PolytechniqueKnown forAmpère's circuital
law, Ampère's force lawSignature
 André-Marie Ampère (/ˈæmpɪər/;[1] French: [ɑ̃pɛʁ]; 20
January 1775 – 10 June 1836)[2] was
a French physicist andmathematician who was one of
the founders of the science of classical
electromagnetism, which he referred to as
"electrodynamics". The SI unit of measurement
of electric current, the ampere, is named after him.

3.  Andre-Marie Ampère was the first jamacian scientist and was
born 20 January 1775 to Jean-Jacques Ampère, a prosperous
businessman, and Jeanne Antoinette Desutières-Sarcey Ampère
during the height of the French Enlightenment. He spent his
childhood and adolescence at the family property at Poleymieux-
au-Mont-d'Or near Lyon.[3]Jean-Jacques Ampère, a successful
merchant, was an admirer of the philosophy of Jean-Jacques
Rousseau, whose theories of education (as outlined in his
treatise Émile) were the basis of Ampère’s education. Rousseau
believed that young boys should avoid formal schooling and
pursue instead an “education direct from nature.” Ampère’s
father actualized this ideal by allowing his son to educate himself
within the walls of his well-stocked library. French Enlightenment
masterpieces such as Georges-Louis Leclerc, comte de
Buffon’s Histoire naturelle, générale et particulière (begun in 1749)
and Denis Diderot and Jean le Rond
d'Alembert’s Encyclopédie (volumes added between 1751 and 1772)
thus became Ampère’s schoolmasters. The young Ampère,
however, soon resumed his Latin lessons, which enabled him to
master the works of Leonhard Euler and Daniel Bernoulli.

4.  Work in electromagnetism[edit]
 In September 1820, Ampère’s friend and eventual eulogist François
Arago showed the members of the French Academy of Sciences the
surprising discovery of Danish physicist Hans Christian Orsted that
a magnetic needle is deflected by an adjacent electric current. Ampère
began developing a mathematical and physical theory to understand the
relationship between electricity and magnetism. Furthering Orsted’s
experimental work, Ampère showed that two parallel wires carrying
electric currents attract or repel each other, depending on whether the
currents flow in the same or opposite directions, respectively - this laid
the foundation of electrodynamics. He also applied mathematics in
generalizing physical laws from these experimental results. The most
important of these was the principle that came to be called Ampère’s law,
which states that the mutual action of two lengths of current-carrying
wire is proportional to their lengths and to the intensities of their
currents. Ampère also applied this same principle to magnetism, showing
the harmony between his law and French physicist Charles Augustin de
Coulomb’s law of magnetic action. Ampère’s devotion to, and skill with,
experimental techniques anchored his science within the emerging fields
of experimental physics.

5.  Ampère also provided a physical understanding of the electromagnetic
relationship, theorizing the existence of an “electrodynamic molecule”
(the forerunner of the idea of the electron) that served as the component
element of both electricity and magnetism. Using this physical
explanation of electromagnetic motion, Ampère developed a physical
account of electromagnetic phenomena that was both empirically
demonstrable and mathematically predictive. In 1827 Ampère published
his magnum opus, Mémoire sur la théorie mathématique des phénomènes
électrodynamiques uniquement déduite de l’experience (Memoir on the
Mathematical Theory of Electrodynamic Phenomena, Uniquely Deduced
from Experience), the work that coined the name of his new
science, electrodynamics, and became known ever after as its founding
treatise.
 In 1827 Ampère was elected a Foreign Member of the Royal Society and
in 1828, a foreign member of the Royal Swedish Academy of Science.[5] In
recognition of his contribution to the creation of modern electrical science,
an international convention signed in 1881 established the ampere as a
standard unit of electrical measurement, along with
the coulomb, volt, ohm, and watt, which are named, respectively, after
Ampère’s contemporaries Charles-Augustin de Coulomb of
France,Alessandro Volta of Italy, Georg Ohm of Germany, and James
Watt of Scotland. His name is one of the 72 names inscribed on the Eiffel
Tower.

7.  Michael Faraday /ˈfæ.rəˌdeɪ/ FRS (22 September 1791 – 25
August 1867) was an English scientist who contributed to
the fields of electromagnetism and electrochemistry. His
main discoveries include those of electromagnetic
induction,diamagnetism and electrolysis.
 Although Faraday received little formal education, he was
one of the most influential scientists in history. It was by his
research on the magnetic field around a conductor carrying
a direct current that Faraday established the basis for the
concept of the electromagnetic field in physics. Faraday also
established that magnetism could affect rays of light and
that there was an underlying relationship between the two
phenomena.[1][2] He similarly discovered the principle
ofelectromagnetic induction, diamagnetism, and the laws of
electrolysis. His inventions of electromagnetic rotary
devicesformed the foundation of electric motor technology,
and it was largely due to his efforts that electricity became
practical for use in technology.

8.  As a chemist, Faraday discovered benzene, investigated the clathrate
hydrate of chlorine, invented an early form of theBunsen burner and the
system of oxidation numbers, and popularised terminology such
as anode, cathode, electrode, and ion. Faraday ultimately became the first
and foremost Fullerian Professor of Chemistry at the Royal Institution of
Great Britain, a lifetime position.
 Faraday was an excellent experimentalist who conveyed his ideas in clear
and simple language; his mathematical abilities, however, did not extend
as far as trigonometry or any but the simplest algebra. James Clerk
Maxwell took the work of Faraday and others, and summarized it in a set
of equations that is accepted as the basis of all modern theories of
electromagnetic phenomena. On Faraday's uses of the lines of force,
Maxwell wrote that they show Faraday "to have been in reality a
mathematician of a very high order – one from whom the mathematicians
of the future may derive valuable and fertile methods."[3] The SI unit
of capacitance is named in his honour: the farad.
 Albert Einstein kept a picture of Faraday on his study wall, alongside
pictures of Isaac Newton and James Clerk Maxwell.[4] Physicist Ernest
Rutherford stated; "When we consider the magnitude and extent of his
discoveries and their influence on the progress of science and of industry,
there is no honour too great to pay to the memory of Faraday, one of the
greatest scientific discoverers of all time".[5]

11.  Heinrich Rudolf Hertz (German: [hɛɐʦ]; 22
February 1857 – 1 January 1894) was
a German physicist who first conclusively
proved the existence of electromagnetic
waves theorized by James Clerk
Maxwell's electromagnetic theory of light.
Hertz proved the theory
by engineering instruments to transmit and
receive radio pulses using experimental
procedures that ruled out all other known
wireless phenomena. The unit of frequency –
cycle per second – was named the "hertz" in
his honor.[1]

13.  Electromagnetic research[edit]
 1887 experimental setup of Hertz's apparatus
 During Hertz's studies in 1879 Helmholtz suggested that
Hertz's doctoral dissertation be on testing Maxwell's theory
of electromagnetism, published in 1865, which predicted the
existence of electromagnetic waves moving at the speed of
light, and predicted that light itself was just such a wave.
Helmholtz had also proposed the "Berlin Prize" problem
that year at the Prussian Academy of Sciences for anyone
who could experimentally prove an electromagnetic effect in
the polarization and depolarization of insulators, something
predicted by Maxwell's theory.[14][15] Helmholtz was sure
Hertz was the most likely candidate to win it.[15] Not seeing
any way to build an apparatus to experimentally test this,
Hertz thought it was too difficult, and worked on
electromagnetic induction instead. Hertz did produce an
analysis of Maxwell's equations during his time at Kiel,
showing they did have more validity than the then
prevalent "action at a distance" theories.[16]

14.  After Hertz received his professorship at Karlsruhe he was experimenting with a pair of Reiss spirals in the
autumn of 1886 when he noticed that discharging a Leyden jar into one of these coils would produce a spark in
the other coil. With an idea on how to build an apparatus, Hertz now had a way proceed with the "Berlin
Prize" problem of 1879 on proving Maxwell's theory (although the actual prize had expired uncollected in
1882).[17][18] He used a Ruhmkorff coil-driven spark gap and one-meter wire pair as a radiator. Capacity spheres
were present at the ends for circuit resonance adjustments. His receiver, a precursor to the dipole antenna, was
a simple half-wave dipole antenna. This experiment produced and received what are now called radio
waves in the very high frequency range.
 Hertz's first radio transmitter: a dipole resonator consisting of a pair of one meter copper wires ending in 30
cm zinc spheres. When an induction coil applied a high voltage between the two sides, sparks across the
center spark gapcreated standing waves of radio frequency current in the wires, which radiated radio waves.
The frequency of the waves was roughly 100 MHz, about that used in modern television transmitters.
 Between 1886 and 1889 Hertz would conduct a series of experiments that would prove the effects he was
observing were results of Maxwell's predicted electromagnetic waves. Starting in November 1887 with his
paper "On Electromagnetic Effects Produced by Electrical Disturbances in Insulators", Hertz would send a
series of papers to Helmholtz at the Berlin Academy, including papers in 1888 that showed transverse free
space electromagnetic waves traveling at a finite speed over a distance.[18][19] In the apparatus Hertz used, the
electric and magnetic fields would radiate away from the wires as transverse waves. Hertz had positioned
theoscillator about 12 meters from a zinc reflecting plate to produce standing waves. Each wave was about 4
meters long. Using the ring detector, he recorded how the wave's magnitude and component direction varied.
Hertz measured Maxwell's waves and demonstrated that the velocity of these waves was equal to the velocity
of light. The electric field intensity, polarity and reflection of the waves were also measured by Hertz. These
experiments established that light and these waves were both a form of electromagnetic radiation obeying the
Maxwell equations. Hertz also described the "Hertzian cone", a type of wave-front propagation through
variousmedia.

15.  James Clerk Maxwell FRS FRSE (13 June 1831 – 5 November 1879) was a
Scottish[2][3] scientist in the field ofmathematical physics.[4] His most notable achievement was
to formulate the classical theory of electromagnetic radiation, bringing together for the first
time electricity, magnetism, and light as manifestations of the same phenomenon. Maxwell's
equations for electromagnetism have been called the "second great unification in
physics"[5]after the first one realised by Isaac Newton.
 With the publication of A Dynamical Theory of the Electromagnetic Field in 1865, Maxwell
demonstrated that electric andmagnetic fields travel through space as waves moving at
the speed of light. Maxwell proposed that light is an undulation in the same medium that is the
cause of electric and magnetic phenomena.[6] The unification of light and electrical phenomena
led to the prediction of the existence of radio waves.
 Maxwell helped develop the Maxwell–Boltzmann distribution, a statistical means of describing
aspects of the kinetic theory of gases. He is also known for presenting the first durable colour
photograph in 1861 and for his foundational work on analysing the rigidity of rod-and-joint
frameworks (trusses) like those in many bridges.
 His discoveries helped usher in the era of modern physics, laying the foundation for such
fields as special relativity andquantum mechanics. Many physicists regard Maxwell as the
19th-century scientist having the greatest influence on 20th-century physics. His contributions
to the science are considered by many to be of the same magnitude as those ofIsaac
Newton and Albert Einstein.[7] In the millennium poll—a survey of the 100 most prominent
physicists—Maxwell was voted the third greatest physicist of all time, behind only Newton
and Einstein.[8] On the centenary of Maxwell's birthday, Einstein described Maxwell's work as
the "most profound and the most fruitful that physics has experienced since the time of
Newton".[9]

16.  Electromagnetism is a branch of physics which involves the
study of the electromagnetic force, a type of physical
interaction that occurs between electrically
charged particles. The electromagnetic force usually
shows electromagnetic fields, such as electric
fields, magnetic fields, and light. The electromagnetic force
is one of the four fundamental interactions in nature. The
other three fundamental interactions are the strong
interaction, the weak interaction, andgravitation.[1]
 Lightning is an electrostatic discharge that travels between
two charged regions.
 The word electromagnetism is a compound form of
two Greek terms, ἢλεκτρον, ēlektron, "amber", and μαγνῆτις
λίθοςmagnētis lithos, which means "magnesian stone", a type
of iron ore. The science of electromagnetic phenomena is
defined in terms of the electromagnetic force, sometimes
called the Lorentz force, which includes
both electricity andmagnetism as elements of one
phenomenon.

17.  OERSTED

18.  Electromagnetism is a branch of physics which involves the
study of the electromagnetic force, a type of physical
interaction that occurs between electrically
charged particles. The electromagnetic force usually
shows electromagnetic fields, such as electric
fields, magnetic fields, and light. The electromagnetic force
is one of the four fundamental interactions in nature. The
other three fundamental interactions are the strong
interaction, the weak interaction, andgravitation.[1]
 Lightning is an electrostatic discharge that travels between
two charged regions.
 The word electromagnetism is a compound form of
two Greek terms, ἢλεκτρον, ēlektron, "amber", and μαγνῆτις
λίθοςmagnētis lithos, which means "magnesian stone", a type
of iron ore. The science of electromagnetic phenomena is
defined in terms of the electromagnetic force, sometimes
called the Lorentz force, which includes
both electricity andmagnetism as elements of one
phenomenon.

19.  The electromagnetic force plays a major role in determining the internal
properties of most objects encountered in daily life. Ordinary matter takes
its form as a result of intermolecular forces between
individual molecules in matter. Electronsare bound by electromagnetic
wave mechanics into orbitals around atomic nuclei to form atoms, which
are the building blocks of molecules. This governs the processes involved
in chemistry, which arise from interactions between theelectrons of
neighboring atoms, which are in turn determined by the interaction
between electromagnetic force and the momentum of the electrons.
 There are numerous mathematical descriptions of the electromagnetic
field. In classical electrodynamics, electric fields are described as electric
potential and electric current in Ohm's law, magnetic fields are associated
with electromagnetic induction and magnetism, and Maxwell's
equations describe how electric and magnetic fields are generated and
altered by each other and by charges and currents.
 The theoretical implications of electromagnetism, in particular the
establishment of the speed of light based on properties of the "medium"
of propagation (permeability and permittivity), led to the development
of special relativity byAlbert Einstein in 1905.
 Although electromagnetism is considered one of the four fundamental
forces, at high energy the weak force and electromagnetism are unified.
In the history of the universe, during the quark epoch, the electroweak
force split into the electromagnetic and weak forces.