Question

Consider the optical interface between crown glass and ethanol. Under what conditions would total internal relfection be possible at this interface? ilustrate your answer with a light ray diagram.
Okay so you need the angle of incidenc to be greater than the critical angle AND the light must be travelling from a medium of higher index refraction into a medium of lower index of refraction.
Im just confused with the diagram part.
I have my axis drawn, with crown glass on top since its higher index of refraction, and then water below. But now I don't know how to draw the arrow.

Answer 1

draw the normal. then, the light in starting from inside the glass, traveling at the angle of incidence, hits the alcohol/glass interface, then is refraced from the normal 90 degrees (tangent to the interface). The incident angle in the glass (measured to the normal) is the critical angle.

Answer 2

so, both arrows should remain on the crown glass side of the axis, correct? t should just sort of look like a "V"?