Questions on Light
Q14.
(a) The diagram shows a ray of light reflecting several times between two parallel mirrors.
(i) What relationship is there between the angle of incidence for the first reflection and the angle of reflection for the last reflection?
They are the same or equal 
1 mark
(ii) At each reflection there is a small loss in the intensity of the light. Suggest one reason why there is a small loss in the intensity of light when it is reflected.
any one from:
- some light is scattered by uneveness of the surface (scattering).
- absorption by the mirror
Do not accept:
- absorption in the air
- 'absorption'
- 'not all of the light is reflected'
1 mark
(b) In the diagram below, the angle of incidence has changed, but the mirrors are in the same positions. State how this change in the angle of incidence would affect the intensity of the emergent ray. Explain your answer.
The intensity would be greater because there are fewer reflections.
2 marks
(c) The two mirrors are now moved so that they are at exactly 30o to each other. The incident ray is parallel to one of the mirrors.
Draw the path of the ray of light on the diagram. Use a ruler and a protractor. Label the emergent ray and draw an arrow to show its direction.
The first mark is for drawing the path of the ray - both parts of the path are required for this mark.
The second mark is for indicating that the ray emerges along the same line as the incident ray but in the opposite direction either a label or an arrow is sufficient.
2 marks
Maximum 6 marks
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