# World’s Super Scientists – Ampere Andre-Marie

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Man behind the live wire of electricity – Ampere, Andre-Marie

Scientist Ampere, Andre-Marie (1775 to 1836), French physicist and mathematician, founder of electrodynamics (now called electromagnetism) was born in 1775 to a hemp merchant. As a boy, he was emotionally upset / moved by the execution of his father in the ‘Reign of Terror’ following the French Revolution.

Scientist Ampere was a prodigy who mastered mathematics by the age of 12, just like Dalton who became headmaster of a school at the age of 12.

1801 Professor of physics and chemistry at Bourg.

1804 his beloved wife died; he plunged himself into scientific work after this blow.

1809 professor of mathematics in an institute in Paris.

Observation : mathematics, physics and chemistry (MPC) is a ‘Royal group’ — versatile for a scientist.

Scientist Ampere published papers on calculus, optics, astronomy, zoology, besides on MPC.

Based on the experiments of Oersted, a Danish scientist, Ampere observed a magnetic needle to move in the vicinity of an electric current; an electric current is capable of exciting a magnetic field; electric currents produce magnetic fields.

In 1823 Scientist Ampere published his famous treatise on magnetism and electricity. Magnetism could be produced with electricity. The space surrounding an electric current is the same kind of field of force that surrounds a magnet. Electricity could produce magnetism (see Faraday, also).

Definition of ampere

i) This is a unit of measurement of flow of electric current popularly called ‘amps’ – 5 amps, 10 amps, etc. A flow of one ampere is produced in a resistance of one ohm by a potential difference of one volt,

ii) Electric current is defined as the amount of charge flowing per second (coulomb, a quantity of electrical charge) and its strength is measured in ampere(A).

1 ampere = 1 coulomb / 1 second.

If two points, between which potential difference exists, are connected by a conductor, the current flows from higher potential (where there is deficit of electrons) to lower potential (where there is excess of electrons) – an analogy :  just as water flows from a higher level to a lower level (easy to understand).

The direction of electric current is opposite to the direction of flow of electrons. Electric Current

Flow of electrons

Excess of electrons

(lower potential)

Deficit of electrons

(higher potential)

An atom consists of a nucleus about which electrons rotate; moving electrons constitute an electric current.

In a Cell

If two electrodes, say a zinc rod and copper rod are joined by a wire, the excess electrons from the zinc rod flow to the copper rod; inside the cell, the current flows from zinc rod to the copper rod whereas outside the cell, i.e., in the external circuit, current flows from the copper rod to zinc rod.

Ampere’s theorem gives the quantitative relationship between the strength of magnetic field produced and electric current.

Scientist Ampere built an instrument devising a free-moving needle to measure the flow of electricity, the principle behind the present day galvanometer.

Gift of science made him join the band of immortals. His name is given to the unit of electric current – the ampere.

amperes (I) = volts(V)/ohms(R) #### JEE Main

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