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Brief History of electromagnetism. Contents. History 1. Ancient times. 2. Mid-times 3. Early modern times. 2. Unification. Ancient times. Amber rubbed with fur attracts bits of dust and hairs. Static electricity - spikes on cold, dry days, lightening.
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Contents • History 1. Ancient times. 2. Mid-times 3. Early modern times. 2. Unification.
Ancient times • Amber rubbed with fur attracts bits of dust and hairs. • Static electricity - spikes on cold, dry days, lightening. • Lode stone compass
Mid-times • 1600. English scientist, William Giber, publishes “De Magnete”. • 1700. Lectures and demonstrations given by various scientists using electricity and entertain audiences
Mid-times • 1700.Ben Franklin(1706-1790) • Two kinds of charges: positive and negative • Like charges repel, unlike charges attract • Conservation of Charges: an isolated system has constant total charge
Mid-times • 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 law. 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 each other. • 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 electromagnetic waves. • 1885. Hertz shows Maxwell was correct and generates and detects electromagnetic waves. • 1895.Guglielmo Marconi puts the discovery to practical use by sending messages over long distances by means of radio signals.
Maxwell’s Equations • Gauss' law for electricity • Gauss' law for magnetism • Faraday's law of induction • Ampere's law
Is there an underlying simplicity behind vast phenomena in Nature? Einstein dreamed to come up with a unified description But he failed to unify electromagnetism and gravity (GR) Einstein’s Dream
Special relativity GR Quantum ElectroDynamics Weak force Electroweak theory Strong force String theory? Grand Unification? History of Unification electric magnetic planets atoms apple electromagnetiesm Quantum mechanics gravity mechanics g-decay b-decay a-decay
The End Thank you!