Question: A convex lens is placed on a plane glass surface and illuminated with sodium light of wavelength 589.3 nm. The diameter of the tenth dark ring is found to be 4.06 nm.
a) what is the radius of curvature of the lower face of the lens?
b) Using another light source, the diameter of the twelfth dark ring was found to be 47.4 mm. Calculate the wavelength of the new light source.