Here is how to read the measurement on this micrometer step-by-step: Main scale (bottom graduation): This indicates whole millimeters. The last visible line is past the 15 mark and corresponds to 16 mm.
Main scale (top graduation): The upper graduations represent half-millimeters (0.5 mm). After the 16 mm line, no intermediate 0.5 mm line is visible before the edge of the thimble. The base reading therefore remains 16.00 mm.
Thimble scale (rotating graduation): The horizontal centerline of the main scale aligns perfectly with the 25
mark on the thimble. Since each thimble graduation represents 0.01 mm, this adds \(25 \times 0.01 = \textbf{0.25 mm}\).
Summing the two values: \[\text{Measurement}=16.50\text{\ mm}+0.25\text{\ mm}=\mathbf{16.75}\text{\ mm}\] Explanatory note on the graduations: Looking closely at the layout, the bottom scale counts whole millimeters (0, 1, 2, 3, 4, 5...),
while the top scale is offset by 0.5 mm. After the number 15, we count 15.5 (top), 16 (bottom), and then the visible upper graduation is the 16.5 mm mark. Adding the 0.25 mm
from the thimble gives a total of 16.75 mm.
If you are practicing for an exam or workshop, I can provide more reading examples or explain how to check a micrometer for zero error. What would you like to do?
