A building contractor needs 500 sheets of drywall. Which is the most cost-effective way to buy them? 50 sheets at a time for $600 100 sheets at a time for $800 250 sheets at a time for $2,500 500 sheets at a time for $4,500

What is the thinnest soap film (excluding the case of zero thickness) that appears black when illuminated with light with a wavelength of 480 ? the index of refraction of the film is 1.34, and there is air on both sides of the film. express your answer in nanometers. hint 1. how to approach th