Physics 5337  Homework #5
 In a system, the period of oscillation T is related to the
wavenumber k by
T [a * k * tanh(b*k)]^{1/2} = 2 π
where a and b are constants.
 What is the group velocity?
 What is the phase velocity?
 What is the speed of sound (long wavelength limit)?
 If T, a, and b are all equal to 1, what is k?

 What is the de Broglie wavelength of a neutron moving at 2000 m/s?
 What is its kinetic energy?
 What is the de Broglie wavelength of an electron moving at 2000 m/s?
 What is its kinetic energy?
 Which is more likely to Bragg scatter from a crystal of NaCl?
 What energy Xray has the same wavelength as the particle above that scatters from NaCl?