The document describes an experiment using water and milk to model how obscuring glass scatters light. Students add drops of milk to water in a beaker and observe how it affects their ability to read a hidden letter. They repeat the experiment multiple times and record the number of drops needed until the letter is no longer readable. This data could help engineers decide how much to obscure bathroom glass to balance privacy and light transmission.

1. Seeing the light February 4, 2011 Please stick in your quiz results, complete the target sheet by adding your score and colouring in the objectives.

13. transparent

15. translucent

19. Considering the evidence 1 Explain why you have been asked to do the experiment three times. 2 How reliable do you think your results are? Explain why you think this. Extension 3 One engineer using this data decides to use a glass mix that is less obscuring, because the amount of light getting through is reduced by making it too cloudy. Another engineer wants to make it more obscure because he wants to ensure privacy in the bathroom. The director of the department decides that the glass should be less obscure. Do you think they are right? What might have made them make this decision? 4 Many types of obscuring glass are not frosted, but have a wobbly surface. Describe how this does the same job. Would this sort of glass be suitable for a bathroom screen? 5 Describe the difference between the way that the milk scatters the light and the surface unevenness scatters the light. Number of drops of milk to obscure letter Average Result three Result two Result one