Brief History of electromagnetism Contents
Transcript Brief History of electromagnetism Contents
Brief History of
1. Ancient times.
3. Early modern times.
Amber rubbed with fur attracts bits of dust and hairs.
Static electricity - spikes on cold, dry days, lightening.
Lode stone compass
1600. English scientist,
publishes “De Magnete”.
1700. Lectures and
by various scientists
using electricity and
Two kinds of charges: positive and
Like charges repel, unlike charges attract
Conservation of Charges: an isolated
system has constant total charge
1785. Charles Austin de Coulomb
The force between two charges Q1 and Q2 is
proportional to their product divided by the
separation distance r squared inverse square
1790. Alessandro Volta finds chemistry acting on
two dissimilar metals generates electricity. He
later invents the voltaic pile-the battery.
Early Modern times
1820. Hans Christian Oersted.
electric current affects compass needle
1820. Adre Marie Ampere in Pairs finds that
wires carrying current produce forces on
1820. Michael Faraday at royal Society
develops the idea of electric field and studies
the effect of currents on magnets and
magnets inducing electric currents.
Early Modern times
1860. James Clerk Maxwell, a Scottish physicist and mathematician,
puts the theory of electromagnetism on mathematical basis.
1873.Maxwell publishes "Treatise on Electricity and Magnetism" in
which he summarizes and synthesizes the discoveries of Coloumb,
Oersted, Ampere, Faraday, et. al. in four mathematical equations.
Maxwell's Equations are used today as the basis of electromagnetic
theory. Maxwell makes a prediction about the connections of
magnetism and electricity leading directly to the prediction of
1885. Hertz shows Maxwell was correct and generates and detects
1895.Guglielmo Marconi puts the discovery to practical use by sending
messages over long distances by means of radio signals.
Gauss' law for electricity
Gauss' law for magnetism
Faraday's law of induction
0c c t
Is there an underlying
simplicity behind vast
phenomena in Nature?
Einstein dreamed to
come up with a unified
But he failed to unify
History of Unification