# Does the angle of incidence change the refractive index?

I've been told if you plot a graph using the sine of the angle of incidence and the sine of the angle of transmission it should follow a linear regression $y = ax + b$. However, if you use certain materials this relationship will not be linear. This can only be possible if the angle of incidence changes the refractive index. What sort of materials have this behaviour? What is the relationship between the refractive index and the angle of incidence?

• See the following link: Snell's_Law – Vadim Chernetsov Apr 23 '16 at 13:55
• What are y and x? – Anubhav Goel Apr 23 '16 at 15:25
• y is the sine of the angle of incidence and x the sine of the angle of transmission – jatrp5 Apr 23 '16 at 16:29