Question

1. Mourning doves have a small patch of iridescent feathers. The color is produced by a 330-nm-thick layer of keratin (n = 1.56) with air on both sides that is found around the edge of the feather barbules.

Part A) For what wavelength or wavelengths in the visible spectrum would this structure produce constructive interference?

2. One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. Having recently studied optics in your physics class, you're not too surprised to see that the patch of light seems to be a circular diffraction pattern. It appears that the central maximum is about 3 cmacross, and you estimate that the distance from the window shade to the wall is about 5 m .

Part A) 

Knowing that the average wavelength of sunlight is about 500 nm, estimate the diameter of the pinhole.

Answer 1