The figure shows refraction of plane waves from air to water using Huygens' construction. With lengths a, b, c, d and e marked in the diagram, which ratio equals the refractive index of water relative to air?

Question

G1 Physics · Accepted Answer

In Huygens' construction, during the same time interval the wave travels distance b in air and distance d in water. Therefore the refractive index of water relative to air equals (speed in air)/(speed in water)=b/d. Option C.