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November 22, 2013

November 22, 2013. Name of the Game:. ENERGY And also: NOBEL PRIZES FOR PHYSICS. Energy, Wavelength, Frequency. Long wavelength Low frequency Low energy Short wavelength High frequency High energy. Wave Model. Max Planck (1918 – Nobel Prize). Studied: Black body radiation

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November 22, 2013

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  1. November 22, 2013

  2. Name of the Game: ENERGY And also: NOBEL PRIZES FOR PHYSICS

  3. Energy, Wavelength, Frequency • Long wavelength Low frequency Low energy • Short wavelength High frequency High energy

  4. Wave Model

  5. Max Planck (1918 – Nobel Prize) • Studied: Black body radiation • Why do hot metals have a different color than cold metals? • Heat is energy • Color is visible light (EMR)

  6. Max Planck (1918 – Nobel Prize) • Energy is only emitted in “small packets” • Quantum: • A small packet of energy • Smallest amount of energy that can be gained or lost by an atom • Planck’s constant: h = 6.626 × 10-34 J· s 1858-1917

  7. Albert Einstein (Nobel Prize - 1921) • Studied: Photoelectric effect • In the photoelectric effect, electrons are emitted from matter when atoms absorb energy from electromagnetic radiation (EMR) • Below a certain frequency of light, no electrons were emitted

  8. Albert Einstein (Nobel Prize - 1921) • Light can behave as a wave AND a particle • “Dual wave-particle” nature of light • Photon: • particle of electromagnetic radiation • carries a quantum of energy • zero mass 1879-1955

  9. The big equation for Energy: The energy (E ) of electromagnetic radiation is directly proportional to the frequency () of the radiation. E = h E = Energy, in units of Joules (kgm2/s2) h = Planck’s constant (6.626 x 10-34 Js) v =frequency (Hz, s-1)

  10. PRACTICE: • What is the energy in Joules of a photon with a frequency of 4.0 × 1011 Hz? • E = hv= (6.626 x 10-34 Js)(4.0 x 1011Hz) = 2.65 x 10-22 J • What is the frequency of a photon with an energy of 7.3 × 10-18 J? • E = hv 7.3 × 10-18 J = (6.626 x 10-34 Js)v (7.3 × 10-18 J)/(6.626 x 10-34 Js) = 1.1 x 1016 Hz

  11. A few examples • Gamma Radiation • Infrared • Ultraviolet • Microwaves

  12. Gamma Radiation • Space! • Nuclear decay • More on Tuesday…

  13. Infrared: Remote Control • “Below red” • How to see it on your camera phone: http://www.wikihow.com/See-Infared-Light

  14. Ultraviolet rays: The Sun Click on the link to see how this experiment worked.

  15. Ultraviolet Rays: BlackLight • What items will show up under a blacklight? • Why do some things phosphoresce under UV light? • Fluorescent substances absorb the ultraviolet light and then re-emit it almost instantaneously. Some energy gets lost in the process, so the emitted light has a longer wavelength than the absorbed radiation, which makes this light visible and causes the material to appear to 'glow'.

  16. Microwave • Mental Floss: Discovery of (1:50) • Minute Physics: How it works

  17. Your task…

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