A ray of light travelling in air is incident on a rectangular glass block and emerges out into the air from the opposite face. Draw a labelled ray diagram to show the completer path of this ray of light. Mark the two points where the refraction of light takes place. What can you say about the final direction of ray of light?

The two points where the refraction of light takes place are : 

(i) At point $O$, when it travels from air to glass.

(ii) At point $Q$, when it travels from glass to air.

The final direction of the light ray is same as the incident direction, i.e., $QR$ will be parallel to the direction $POS$ in which it enters the glass block.