Is refractive index on each side of the parallelepiped the same?

[Dorea]

Refractive index on each side of a rectangular cube parallelepiped: n1, n2, n3
Is this correct: n1=n2=n3?

http://image.bayimg.com/01c243801d8868097dbe98fb599b0d6aa9fb2e7d.jpg

 

[nasu]

If n2 is the index of the rectangular object, then no.

 

[sophiecentaur]

Afair, the refractive index refers to a substance and not a surface. The picture appears to be of an isotropic object in air so all that's involved is the index of air (= nearly 1) and the index of the object material.
Is there some other definition that I don't know about or could you rephrase the question so that it makes sense to me please?

 

[Dorea]

Any birefringence plate has tree side. we ha a birefringence plate with tree different side in size. The question is this: Is index of refraction of this birefringence plate related to the distance which light travels through it?! In other words, each side of this plate have a different refractive index or not?