The planes of atoms in a cubic crystal lie parallel to the surface, 0.87 nm apart. X rays having wavelength 0.41 nm are directed at an angle θ to the surface.
a) For how many values of θ will there be a strong reflection?
b) What is the largest value of θ that gives a strong reflection?
c) What is the second largest value of θ that gives a strong reflection?
d) What energy electrons could give the same result?