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Electromagnetic Waves

History: 1864- James Clerk Maxwell developed a theory to explain the basic nature of electromagnetic waves (Maxwell’s equations). Electromagnetic Waves. 1887- Heinrich Hertz experimentally verified Maxwell’s predictions with the production and detection of radio waves in his lab.

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Electromagnetic Waves

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  1. History: 1864- James Clerk Maxwell developed a theory to explain the basic nature of electromagnetic waves (Maxwell’s equations) Electromagnetic Waves 1887- Heinrich Hertz experimentally verified Maxwell’s predictions with the production and detection of radio waves in his lab 1901- Marconi demonstrated long-range radio wave transmission between Britain and Newfoundland 1906- Reginald Fessenden (Canadian!) produced the first modulated radio transmission with voice and music An Introduction to Electromagnetic Waves Radio Waves

  2. How EM Waves are Generated :  accelerated electric charges (eg. electrons oscillating up and down in an antenna) lose energy  energy is carried away as an electromagnetic wave-the frequency is determined by the charge oscillation Oscillating charges produce EM waves! C=3.0 x 10 8 m/s  Speed of ALL EM waves in a vacuum is ___________ (the speed of _______!) light  This is predicted theoretically by an equation that includes both the electric and magnetic properties of free space: where 0 = magnetic permeability 0= 1/4K (K= Coulomb’s constant)

  3. How EM Waves Propagate: • Two key principles involved in EM wave transmission : • 1) A changing electric field produces a magnetic field • 2)A changing magnetic field produces an electric field • The changing electric and magnetic fields produced are linked- • one produces the other as they propagate through space • The resulting __________ EM wave consists of • electric and magnetic fields which are: • 1) oscillating IN PHASE • (both go to zero at same time) 2) Oriented perpendicular to each other 3) Oriented perpendicular to the direction of propagation EM waves travel as coupled, oscillating Electric and Magnetic Fields!

  4. The Electromagnetic Spectrum Radio Waves Decreasing Wavelength Increasing Frequency Increasing Energy Microwaves Non-Ionizing Radiation Infrared Radiation Visible Light Ultraviolet Light Ionizing Radiation -high energy radiation which can break chemical bonds and cause cellular damage X-Rays Gamma Rays

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