refractive index... snell's law... help!! Hi, im having a LOT of trouble with what seems like a basic question. i have been stressing over this for nearly 3 hours now. can anyone help me out? here it is: Light propagating from water into air is incident on the water surface at the angle of total internal reflection. A plane parallel glass plate is brought into contact with the surface of water. Will any light be observed as a result of that? Justify your answer by using Snell’s law. snell's law: n1sin [tex]\theta[/tex]1 = n2sin[tex]\theta[/tex]2 where n is the refractive index of the medium either side of the boundary, and theta is the angle made by the ray with the normal to the boundary either side of the boundary. all i have managed to work out is that the light ray coming in at the reflection angle for water - air boundary would not be able to experience total internal reflection at a water - glass boundary, since the refractive index of glass is greater than water. when the ray travels through the glass and meets the glass - air boundary, total internal reflection is possible since air has a lower refractive index than glass. but, i am stuck here. i cant find a way to show whether the ray will be totally internally reflected or not. has anyone got any suggestions? thanks.