Calibrating eyepiece graticule with stage micrometer

Steps:

• Total stage micrometer length: 40 divisions × 0.04 mm/division = 1.6 mm.
• This 1.6 mm aligns exactly with 50 eyepiece divisions under ×40 objective.
• Actual size per eyepiece division: 1.6 mm / 50 = 0.032 mm.
• ×40 magnification positions the scales for alignment but does not alter the ratio.

Why B is correct:

• B states each eyepiece division equals 0.032 mm, per calibration formula: actual length per eyepiece unit = total stage length / eyepiece divisions spanned.

Why the others are wrong:

• A incorrectly uses stage division size (0.04 mm) without scaling to eyepiece divisions.
• C miscalculates total stage length as 40 × 0.01 mm or similar, yielding wrong ratio.
• D applies magnification directly (e.g., 0.04 mm / 40), ignoring eyepiece scale.

Final answer: B