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De Brogli wavelengths Contents: de Broglie wavelengths Example 1 Whiteboards

De Brogli wavelengths Contents: de Broglie wavelengths Example 1 Whiteboards Transmission electron microscopes Scanning electron microscopes Scanning tunneling electron microscopes. Louis de Broglie. Light is acting as both particle and wave Matter perhaps does also E = hf = hc/ 

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De Brogli wavelengths Contents: de Broglie wavelengths Example 1 Whiteboards

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  1. De Brogli wavelengths • Contents: • de Broglie wavelengths • Example 1 • Whiteboards • Transmission electron microscopes • Scanning electron microscopes • Scanning tunneling electron microscopes

  2. Louis de Broglie • Light is acting as both particle and wave • Matter perhaps does also • E = hf = hc/ • E = mc2 • mc2 = hc/ • mc = p = h/ • p = h/ • p = momentum (p = mv) • h = Planck’s constant (6.626 x 10-34 Js) •  = de Broglie wavelength TOC

  3. p = h/ • p = momentum (p = mv) • h = Planck’s constant (6.626 x 10-34 Js) •  = de Broglie wavelength Example 1: What is the de Broglie wavelength of a .50 kg ball going 40. m/s? p = mv = (.50 kg)(40. m/s) = 20. kg m/s p = h/,  = h/p = (6.626 x 10-34 Js)/(20. kg m/s) = 3.31 x 10-35 m Golly - nothing is that small (atoms are 10-10 m) How would you observe the wave behaviour of that? TOC

  4. Whiteboards: de Broglie Wavelength 1 | 2 | 3 TOC

  5. What is the de Broglie wavelength of an electron going 1800 m/s? (3) m = 9.11 x 10-31 kg p = mv p = h/ p = (9.11 x 10-31 kg)(1800 m/s) = 1.6398 x 10-27 kg m/s  = h/p = (6.626 x 10-34 Js)/(1.6398 x 10-27 kg m/s) = 404 nm W 404 nm

  6. What is the momentum of a 600. nm photon? p = h/ p = (6.626 x 10-34 Js)/(600. x 10-9 m) = 1.10 x 10-27 kg m/s W 1.10 x 10-27 kg m/s

  7. A 300. MW 620. nm laser is putting out 9.36 x 1026 photons per second. since F = p/t, and t = 1 second, what is the total thrust of the laser? (2) for 1 photon: p = h/ for 5 photons: 5p = 5h/ p = (6.626 x 10-34 Js)/(620. x 10-9 m) = 1.0687 x 10-27 kg m/s total p change = (9.36 x 1026 )(1.0687 x 10-27 kg m/s) = 1.00 N W 1.00 N

  8. Applications of “matter” waves • Electron Microscopes • Image resolution  •  = h/p • Electric or magnetic lenses • Gertrude Rempfer (PSU) TOC

  9. Scanning electron microscope

  10. Scanning tunneling electron microscope Actually can image atoms and molecules

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