The following question appeared on one of my exam papers. A CCD of pixel density 10Mpixel (1cm^-2) is used to image a component of length 10cm. Show how this does or does not meet the required accuracies of +/- 0.025mm. A similar question was asked in a previous exam where the component's length was 10cm but a width of 1cm was also specified. I would like to know whether or not both length and width are required in order to determine a solution. I was of the impression that both dimensions would be needed but my lecturer disagrees. Can anyone clarify the situation?