Draw a labelled ray diagram to show how a ray of light passes through a parallel sided glass block : (a) if it hits the glass block at 90° (that is, perpendicular to the glass block) (b) if it hits the glass block at an angle other than 90° (that is, obliquely to the glass block).

Q. Consider a light wave that passes from air into a very thick clear glass block that has its opposite internal side mirrored (facing into the glass). The light ray passes into the glass block at an angle greater than $0^{\circ }$ and less than ${90}^{\circ }$, strikes the mirrored surface and reflects back through the glass into the air.
What happens while the light ray is in the glass block but before it strikes the mirrored surface?

Q. The diagram given alongside shows a ray of light entering a rectangular block of glass.

(a) Copy the diagram and draw the normal at the point of entry.
(b) Draw the approximate path of the ray of light through the glass block and out of the other side.

Figure

Q. A ray of light travelling inside a rectangular glass block of refractive index $\sqrt{2}$ is incident on the glass-air surface at an angle of incidence of ${45}^{}$. Show that the ray will emerge into the air at an angle of refraction equal to ${90}^{}$.

Q. When a ray of light passes through a rectangular glass block, the direction of emergent ray is .......... to the incident ray.