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Homework Help: Matter Waves

  1. Oct 5, 2008 #1
    1. The problem statement, all variables and given/known data
    Electrons are accelerated from rest by a voltage of 59.0 V. After that acceleration:
    1.What is their speed?
    2.What is their De Broglie wavelength?
    3.The accelerated electrons are then reflected by a crystal with crystal spacing d of 0.085 nm. Through which angle are they reflected?

    h = 6.63 × 10–34 J.s, c = 3 × 108 m/s, Mass of e = 9.11 × 10–31 kg, e = 1.6 × 10–19 C.
    2. Relevant equations



    3. The attempt at a solution
    1. √((2*e*V)/massofe) = √((2*1.6 × 10–19 *59)/9.11 × 10–31 ) = 4552414.59 m/s
    2. λ = h/p = h / √(2*h*e*massofe) = 6.63 × 10–34 / √((2*1.6 × 10–19 * 9.11 × 10–31 ) * (1E-9) = 0.16 nm
    3. 2dsin (θ) = m λ
    = sin-1 (1* 0.16 / (2 * 0.085)) = 70 ........<=== i m stuck because the answer in the book is 39.8
    i really need help
     
    Last edited: Oct 5, 2008
  2. jcsd
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