Ebook Physical Laboratory Experiments

Object. - The object of this experiment is twofold - first, to determine the value of the inch in terms of the millimeter, and second, to give the student practice in estimating by eye, tenths of a small division. The ability to make accurately such estimations is of great importance in all scientific work as the experimenter is continually obliged to estimate fractions, usually tenths, of the smallest division of his instrument e.g. tenths of a degree, tenths of a millimeter, etc. The computation also introduces the student to some fundamental matters in the precision discussion of direct measurements.

Apparatus. - The apparatus consists of a micrometer screw, M, mounted horizontally and carrying a movable nut on which is a fine reference mark, N. The nut moves between two horizontal scales. S1 and S2; the graduations of which are flush with the reference mark on the nut, thus eliminating errors in reading arising from parallax. The scale S1 is graduated in twentieths of an inch. The scale S2 is graduated in millimeters corresponding to the pitch of the micrometer screw.