Question

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.

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

Answer 1

The small patch of iridescent feathers in Mourning doves is produced by thin film interference. Constructive interference occurs when the thickness of the keratin layer and the wavelength of light satisfy the condition for constructive interference.

Step-by-step explanation:

The iridescent color produced by the Mourning doves is due to thin film interference. Constructive interference occurs when the thickness of the layer of keratin and the wavelength of light satisfy the condition for constructive interference. In this case, the thickness of the keratin layer is 330 nm.

Constructive interference occurs when the path length difference is equal to an integer multiple of the wavelength of light. The path length difference is given by 2nt, where n is the refractive index of keratin and t is the thickness of the layer.

For visible light, which has a wavelength range of approximately 400-700 nm, the keratin layer can produce constructive interference for wavelengths within this range. However, since the thickness of the layer is fixed at 330 nm, only certain wavelengths within the visible spectrum will satisfy the constructive interference condition.