PART 1: Relating X-ray Energy, Wavelength, and Penetrating Power Recall the Einstein EQ: E = hc/ where E is energy, h is Plancks constant (4.136x10-18 keVs), c is velocity (2.998x1017 nm/s) and is wavelength. For a series of X-rays of different energies (i.e., wavelengths) moving from a vacuum into a material (e.g., a mineral), the greater the energy an X-ray has, the more penetrating power it has (i.e., higher energies will penetrate deeper into the sample). Recall that the refractive index of a material (n) is related to the speed of light (c) over the velocity of light in that material (v): n = c/v Determine the velocity of light for each of the three materials (water, quartz, lead) using their refractive indices (nwater = 1.33 , nquartz = 1.4585, nlead = 2.6). You may round to the third decimal place for simplicity. Water: v = c / 1.33 = ____________ nm/s Quartz: v = c / 1.4585 = ____________ nm/s Lead: v = c / 2.6 = ____________ nm/s