A molded plastic panel has microscopic ridges spaced about apart

PHYSICS · Single correct · CBSE · Physics · Light — Reflection and Refraction · Light — Reflection and Refraction

Problem

A molded plastic panel has microscopic ridges spaced about

8\,\mu\text{m}

apart. The panel is illuminated separately by two monochromatic beams: (I) violet light with wavelength

\lambda_1 = 400\,\text{nm}

(II) far-infrared radiation with wavelength

\lambda_2 = 16\,\mu\text{m}

Which combination of reflection types is most likely observed from the panel? (a)

(I)\text{ specular},\ (II)\text{ diffuse}

(b) Both diffuse (c)

(I)\text{ diffuse},\ (II)\text{ specular}

(d) Both specular