Ⅰ. André-Marie Ampère (20th Jan 1775 - 10th Jun 1836)


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By - Sheila Terry

He was born in Lyon, Kingdom of France & is one of the founders of classical electromagnetism which he referred to as 'electrodynamics'. He was a French physicist & mathematician who invented numerous applications, such as solenoid & the electrical telegraph.

As an autodidact, Ampere was a member of the French Academy of Science & a professor at the École Polytechnique & Collège de France.

 He got inspired by the discovery of Danish physicist Hans Christian Ørsted that a magnetic compass needle is deflected by an adjacent electric current.

He developed a mathematical & physical theory to study the relationship between electricity and magnetism. He also showed that two parallel wires carrying currents attract or repel each other, depending on the direction of their flow. This laid the foundation of electrodynamics. 

He generalized the physical laws from these experimental results & developed the most important principle called Ampère's Law, which states that the mutual action of two lengths of current-carrying wire is directly proportional to their lengths & to the intensity of the current. 

He also applied this law to magnetism showing a relationship between his law & Charles Augustin de Coulomb's Law of magnetic action. He also theorized the existence of an 'electrodynamic molecule' (the forerunner of the idea of an electron) that served as the component element of both electricity and magnetism.

In 1827, Ampère published his Magnum Opus (Memoir on the Mathematical Theory of Electrodynamics Phenomena, Uniquely Deduced from Experience). He was then elected a Foreign Member of the Royal Society & in 1828, a Foreign Member of the Royal Swedish Academy of Science. 

James Clerk Maxwell named Ampère "The Newton of Electricity" in his "Treatise on Electricity and Magnetism". In recognition of his contribution to modern electrical science, an international convention, signed at the 1881 International Exposition of Electricity, established ampere as the standard unit of current measurement & his name is one of the 72 names inscribed on the Eiffel Tower. 


Ⅱ. Archimedes (c.287 BC - c.212 BC) 

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He was a Greek mathematician, physicist, engineer, inventor & astronomer born in Syracuse, Sicily in Magna Graecia. He is regarded as one of the leading scientists & the greatest mathematician of the classical age.

He predicted modern calculus & analysis by applying the concept of infinity small & method of exhaustion to derive a variety of geometric theorems like : 

  • area of circle, ellipse & spiral, 
  • the volume of a sphere, segment of a paraboloid & hyperboloid of revolution, 
  • the surface area of sphere & area under a parabola. 

He also derived an accurate approximation of Ï€, founded hydrostatics & statics. His achievements in this area include an explanation of the principle of lever, centre of gravity & buoyancy law. 

He discovered the principle of buoyancy when he was ordered to determine the purity of a gold crown by King Hiero II of Syracuse. This principle was named Archimedes Principle in his honour which states that a body immersed in a fluid, experiences a buoyant force equal to the weight of the fluid it displaces. 

Some of the machines invented by Archimedes include : 

1. The Archimedes Screw 

  • Used to transfer water & other materials from low lying areas. 

2. Claw of Archimedes 

  • Known as the ship shaker.
  • Suspended a large metal grappling hook which was thrown onto the attacking ships 
  • A crane-like arm would lift the ship out of the water & sink it. 

3. Heat Ray

  • Designed by using many mirrors 
  • Placed at specific angles acting as parabolic reflectors 
  • Focused sunlight onto the approaching ships & caused them to catch fire. 

Archimedes's written works include nine extant treatises in Greek which are as follows : 

1. On the Sphere & Cylinder 

  • He derived that the surface area of a sphere is four times that of its greatest circle (S = 4Ï€r²) 
  • The volume of a sphere is 2/3rd of the volume of a cylinder. 

2. Measurement of the Circle 

  • He approached determining the value of Ï€ by inscribing & circumscribing polygons with many sides. 
  • Found it to lie between the limits of 3.1408 & 3.1428. 

3. On Conoids & Spheroids 

  • Determines the volume of segments of solids formed by the revolution of a conic section about its axis. 

4. On Spirals 

  • Develops many properties of tangents & areas associated with it. 
  • Spiral of Archimedes i.e. the locus of a point moving with constant speed along a straight line that itself is rotating with constant speed about a fixed point. 

5. On the Equilibrium of Planes 

  • Establishes the centres of gravity of different rectilinear figures, segments of parabola & paraboloid. 

6. Quadrature of the Parabola 

  • Demonstrates the area of any segment of a parabola is 4/3rd of the area of a triangle having the same base & height as the segment. 

7. The Sand-Reckoner 

  • Improves the inadequacies of the Greek numerical notation system by showing how to express huge numbers. 
  • Created a place-value system of notation, with a base of 100,000,000 to calculate the exact number of grains of sand that would take to fill the entire universe. 

8. Method Concerning Mechanical Theorems 

  • A mechanical method to find the area of a parabolic segment, surface area & volume of a sphere 
  • Divide the two figures into an infinite but equal number of infinitesimally thin strips 
  • Weigh each of these strips on a notational balance to obtain the ratio of the two original figures. 

9. On Floating Bodies 

  • First known work on hydrostatics 
  • Determine the position that different solids will assume when floating in a fluid, according to their form & variation in their specific gravities.