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Unformatted text preview: Electromagnetic Waves 1 Maxwells Predictions During the early stages of studies of electric and magnetic phenomena, they were thought to be unrelated. In 1865, James Clark Maxwell pro- vided a mathematical theory that showed a close relation between electric and magnetic phenomena. His theory is based upon the following 4 pieces of information: 1. Electric fields originate on positive charges and terminate on negative charges. 2. Magnetic field lines always form closed loops. 3. A varying magnetic field induces an emf and hence an electric field (Faradays law of induction). 4. Magnetic fields are generated by moving charges. Dr.D.Wackeroth Spring 2005 PHY102A Electromagnetic Waves Maxwells theory also predicted that electric and magnetic fields can move through space as waves. He calculated their speed to be equal to the speed of light c = 3 10 8 m/s and concluded that light waves are electromag- netic in nature . In other words, light consists of fluctuating electric and magnetic fields that travel through space as transverse waves. Dr.D.Wackeroth Spring 2005 PHY102A Electromagnetic Waves 2 Hertzs Discoveries In 1887, Heinrich Hertz was the first to generate and detect electromagnetic waves in a laboratory experiment. Schematic of Heinrich Hertzs first transmitter and receiver of electromag- netic waves: He also measured the speed of the electromagnetic waves, verifying that Maxwells prediction that they travel at the speed of light was correct.Maxwells prediction that they travel at the speed of light was correct....
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- Fall '10