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Electromagnetic Waves

Electromagnetic Waves. CHARITY I. MULIG. Def’n : EM Wave. Energy-carrying wave emitted by vibrating charges (often electrons) that is composed of oscillating electric and magnetic fields that regenerate one another. . The EM Spectrum.

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Electromagnetic Waves

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  1. ElectromagneticWaves CHARITY I. MULIG

  2. Def’n: EM Wave • Energy-carrying wave emitted by vibrating charges (often electrons) that is composed of oscillating electric and magnetic fields that regenerate one another.

  3. The EM Spectrum Range of frequencies over which electromagnetic radiation can be propagated.

  4. Change in frequency of a wave of sound or light due to the motion of the source or the receiver. • Where • fl is the apparent frequency • f0 is the original frequency • v is the speed of the wave in the medium • v0 is the speed observer relative to the medium; positive if the observer is moving towards the source • vs is the speed of the source relative to the medium; positive if the source is moving away from the observer.

  5. Doppler Effect for EM Waves Observed Frequency Change in Frequency • vs,r = vs – vris the velocity of the source relative to the receiver; it is positive when the source and the receiver are moving further apart. • λo is the wavelength of the transmitted wave in the reference frame of the source.

  6. Def’n: Polarization • Aligning of vibrations in a transverse wave, usually by filtering out waves of other directions.

  7. Wavefronts vs. Rays Huygen’s Principle “The wave fronts of light waves spreading out from a point source can be regarded as the overlapped crests of tiny secondary waves – wave fronts are made up of tinier wave fronts”

  8. Properties of EM Waves • Reflection • Refraction • Diffraction • Dispersion • Scattering • Interference • Polarization

  9. Geometric Optics

  10. Reflection

  11. Types of Reflection Specular/Regular Diffused/Irregular

  12. The open-mesh parabolic dish is a diffuse reflector for short-wavelength light but a polished reflector for long-wavelength radio waves.

  13. Law of Reflection • The incident, reflected and normal ray all lie in the same plane. • The angle of incidence is equal to the angle of reflection.

  14. Reflection at a Plane Surface

  15. Locating Plane Mirror Image

  16. Guidelines for Ray Diagrams

  17. Ray Diagram For Concave Mirrors

  18. Ray Diagram for Convex Mirrors

  19. Mirror Equation and Lateral Magnification

  20. Mirror Equation Sign Convention

  21. Sample Problems

  22. Refraction

  23. Fermat’s Principle of Least Time • Pierre Fermat • Out of all possible paths that light might travel to get from one point to another, it travels the path that requires the shortest time.

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