台湾中华大学-电磁理论课程.pptVIP

Part II.1History of Electro-MagneticTheorem 中華大學 通訊系 田慶誠 tien@chu.edu.tw 03 5186030, 5186398 Outlines Early Investigations of Electricity and Magnetism Linking Magnetism and Electricity Generation of Electric Power Electric Communications Electromagnetic Theory Electromagnetic Waves Radio Communications Early Investigations of Electricity and Magnetism B.C. 600 Thelas (Greek) Math. Astr. Phil. Amber = elektron (Greek) Electricity, electron, electronic Loadstone, found in Magnesia = Magnet, Magnetism Early Investigations of Electricity and Magnetism A. D. 1600 William Gilbert (English) Systematic experiments of electrostatic effects Recognized that the earth is a huge magnet Principles of compass Early Investigations of Electricity and Magnetism 1752 Benjamin Franklin (American) Established conservation of charge Positive (glass) and Negative (hard rubber) charges were named. Kite experiment Early Investigations of Electricity and Magnetism 1785 Charles Augustin de Coulomb (French) Measured electric and magnetic forces Coulomb’s Law Early Investigations of Electricity and Magnetism 1800 Alessandro Volta (Italian) Invented voltaic cell (Chemical Battery) Early Investigations of Electricity and Magnetism 1813 Karl Friedrich Gauss (German math. astr.) Enuciated divergence theorem Gauss’s Law 1832 Gauss and Weber measured the earth’s magnetic field: 500 mgauss Linking Magnetism and Electricity 1819 Hans Christian Oersted (Danish) Discovered Electricity can produce Magnetism E M are related Linking Magnetism and Electricity 1820 Jean Baptiste Biot, Felix Savart Biot-Savart law Linking Magnetism and Electricity 1820 Andre Marie Ampere (French) Ampere’s law of magnetic force Linking Magnetism and Electricity 1820 Andre Marie Ampere (French) Motor equation Three-pole DC Motor Linking Magnetism and Electricity Invented the solenoid coil Ampere’s circuital law The atoms in a magnet are magnetized by tiny electric currents circulating in them Linking M