Exam style questions

Question 1.
X-rays with a wavelength of 1.5 x 10^-10 m are being used for x-ray crystalography. The crystal being investigated has an interatomic spacing of or 2.1 x 10^-10 m. Would you expect to observe a diffraction pattern. Justify your answer.

Answer
Yes, you would expect to observe diffraction. The ratio of wavelength to spacing is:

Any ratio greater than 0.1 will certainly result in observable diffraction.