1. The problem statement, all variables and given/known data Imagine that you are in a vehicle at night on a long straight road. There are no streetlights and one vehicle up ahead in the distance. Estimate how far away the other vehicle would be for its tail-lights to appear as a single orange/red blob. In your answer, make quantitative estimates to characterise: • the colour of the light emanating from the tail-lights • the spatial separation of the tail-lights • the size of the pupil of your dark-adapted eye. 2. Relevant equations 3. The attempt at a solution red light has lambda = 700nm (700*10^-9m) but now i am not sure what to do. I need to equate/use lambda, lense of an eye and focal length/distance to car.