When white light travels through glass, the phase velocity of each wavelength depends on the wavelength. This is the origin of dispersion and the breaking up of white light into its component colors-different wavelengths travel at different speeds and have different indices of refraction. How does vphase depend on lambda? Is dvphase/dlambda positive or negative? Therefore, is vgroup>vphase or <vphase?

In what regions of the electromagnetic spectrum is the atmos- phere transparent enough to allow observations from the ground?

Why can’t we see stars in the daytime?

For a human eye with a pupil diameter (aperture diameter D) of 0.005 meters, and a focal length of 0.022 meters, there will be a resolution limit due to diffraction at 0.6 microns (10^-6 meters) wavelength. If we space light-sensitive cells on the retina at this spacing, how many retina cells per meter (of retina) are there? cells/meter. Now suppose there are giants which are exactly twice the size of humans in each dimension. So giant eyes have pupils of 0.01 meters, and a focal length of 0.044 meters. How many retina cells per meter should the giants have? cells/meter