GCSE questions on refraction and TIR

Q3. Light usually changes direction as it passes from one medium into another. This occurs when the angle of incidence on the medium boundary is greater than 0o.

(a) Name the process that results in a change of direction when light passes from one medium to another.

 (1 mark)

(i) When light passes from air into a glass block, it changes direction in such a way that it moves:

away from the normal  
towards the normal  
to always travel along the normal  

 (1 mark)

(ii) When light passes from glass out into the air, it changes direction in such a way that it moves:

away from the normal
 
towards the normal
 
to always travel along the normal
 

 (1 mark)

(b) Name the process that results in a ray of light 'rebounding' when it hits another medium.

(1 mark)

(c) Name the process that occurs when a ray hits the boundary between a dense optical medium (such as glass) and a rare optical medium (such as air) at an angle of incidence that is greater than the 'critical angle'.

(1 mark)

(d) The diagram shows the path of a light ray through part of an optical fibre.

(i)      Give one practical use for optical fibres.

(1 mark)

(ii)      Explain, as fully as you can, why the light ray stays inside the optical fibre.

(2 marks)

(Total 8 marks)