1. The problem statement, all variables and given/known data 1. I have been recently wondering how is data stored on and retrieved from optical devices like CDs, DVDs, and Bluray. What makes these different storage types different from each other? 2. Why will a silver mirror not show a reflection when you sand the surface with very coarse sandpaper? 2. Relevant equations 3. The attempt at a solution 2. Is it because the coarse sandpaper will make small dents in the material, so the light will reflect off the surface in multiple directions, making it hard to see a clear image or is it because of another reason?