How fast is a wave with a wavelength of 0.1 m and a frequency of 50 hz travelling?
a. 0.002 m/s
b. 1 m/s
c. 5 m/s
d. 50 m/s

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