physics refraction help please..
A ray of the light incident on the slab of transparent material is partly reflected from the surface and partly refracted into the slab . The reflected rays are mutually perpendicular .The incident ray makes an angle i with the normal to the slab . The refractive index of the slab is?
- tan -1 (i)
- cot-1 (i)
- sin-1 (i)
- cos-1 (i)