Week 1Electrostatics

A brief history of the science of electric forces …

Mystery of the Physical World

Thales of Miletus(624 – 546 BC)

..considered the first philosopher in the history of Western Civilization.

Thales observed that when amber is rubbed with animal fur, it exerts weak forces, e.g., attracts small bits of straw or feathers.

William Gilbert(1544 – 1603)

Scientist and physician (Queen Elizabeth was one of his patients) Gilbert showed that many other material besides amber acquire the ability to exert forces when rubbed with another material.

He coined the word “electricity” from the greek word for amber (hlektron) for this phenomenon.

Franklin began as an amateur in electricity, but became a famous scientist.

His important theoretical idea: the “one-fluid model” – that electricity is carried by a single fluid and an object can be positive (excess of fluid) or negative (deficit of fluid). Conservation of charge

His famous kite experiment showed that lightning is an electric discharge.

Benjamin Franklin(1706 – 1790)

Coulomb’s torsion balance

Charles Augustin de Coulomb (1736 – 1806)

The discovery of the electron(J J Thomson, 1897)

Thomson: The cathode ray is a beam of identical particles –- electrons.