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Electromagnetic Energy

Electromagnetic Energy. Prepared by: Timothy John D. Matoy. First described by ancient Greeks Today, they are known as electromagnetic Energy No mass, no identifiable form They do have electric and magnetic fields that are continuously changing in sinusoidal fashion. Photons.

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Electromagnetic Energy

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  1. Electromagnetic Energy Prepared by: Timothy John D. Matoy

  2. First described by ancient Greeks • Today, they are known as electromagnetic Energy • No mass, no identifiable form • They do have electric and magnetic fields that are continuously changing in sinusoidal fashion. Photons

  3. A photon is the smallest quantity of any type of electromagnetic energy. • A photon may be pictured as a small bundle of energy, sometimes called quantum. Photons

  4. Late in 19th century. • Showed that visible light has both electric and magnetic properties, hence the term electromagnetic energy. James Clerk Maxwell

  5. It can travel through empty space. • It travels with the speed of light. • It travels in a wave-like fashion. Properties of EM Radiation

  6. The velocity of all electromagnetic radiation is 3 x108 m/s or 186,000 miles per second. Velocity

  7. The distance from one crest to another, from one valley to another, or from any point on the sine wave to the next corresponding point. Wavelength

  8. Is the number of wavelength that pass a point of observation per second. Frequency

  9. V = λf • Velocity = wavelength x frequency Wave Equation

  10. C = λf • Speed of light = wavelength x frequency Electromagnetic Wave Equation

  11. The highest energy x-ray produced at 120 kVp has a frequency of 2.50 x1019 Hz. What is the wavelength? Practice problem

  12. What is the frequency of a certain electromagnetic wave with a wavelength of 300 cm? Practice Problem

  13. The speed of sound in air is approximately 340 m/s. The highest treble tone that the person can hear is about 20 kHz. What is the wavelength of this sound? Sample problem

  14. The frequency range of electromagnetic energy extends from approximately 102 to 1024 Hz. • The wavelength are approximately 107 to 10-16 m. Electromagnetic Spectrum

  15. Electromagnetic Spectrum

  16. What your eye detects • Has a wavelength of 4000 to 8000 angstroms • 1 angstrom = 1.0 x10-10 m • 1 nm = 1.0 x10-9 m = 10 angstrom Visible light

  17. Relatively low energy and relatively very long wavelength Radiofrequency

  18. Gamma ray • X-ray Ionizing Radiation

  19. Photons interact with matter most easily when matter is approximately the same size as the photon wavelength. • All radiation with wavelength longer than those of x-radiation interacts primarily as a wave phenomenon. Wave-Particle Duality

  20. “X-rays are created with the speed of light (c), and they exist with the velocity (c) or they do not exist at all” – Max Planck Quantum Theory

  21. E = hf • Where: • E = photon energy • h = Planck’s constant • f = photon frequency Planck’s Quantum Equation

  22. Also known as Planck’s constant (h), has a numeric value of 4.15 x10-15eVsor 6.63 x10-34Js. The Constant of Proportionality

  23. What is the frequency of a 70 keV x-ray? Sample problem

  24. What is the energy of a 960 kHz electromagnetic wave? Practice Problem

  25. What is the frequency of a 86 keV x-ray? Practice Problem

  26. Law of conservation of matter • Law of conservation of energy Matter and Energy

  27. E = mc2 • Where: • E = energy in joules • m = mass in kg • c = velocity of light in m/s • 1 Joule = 6.24 x1018eV Theory of Relativity

  28. What is the energy equivalence of an electron (mass = 9.109 x10-31 kg), as measured in joules and electron volts? Sample problem

  29. What is the mass equivalence of a 90 keV x-ray? Practice Problem

  30. What is the mass equivalence of a 340-nm photon of UV light? Practice Problem

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