How many divisions are graduated on the thimble of micrometer?

How many divisions are graduated on the thimble of micrometer? Correct Answer 50

Concept:

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The micrometer is a precision instrument used to measure a job, generally within an accuracy of 0.01 mm.

Working Principle:

• The micrometer works on the principle of screw and nut
• The longitudinal movement of the spindle during one rotation is equal to the pitch of the screw.

Graduations of metric micrometer:

• In metric micrometer, the pitch of the spindle thread is 0.5 mm
• Thereby, in one rotation of the thimble, the spindle advances by 0.5 mm
• On the barrel/sleeve a 25 mm long datum line is marked
• This line is further graduated to millimeters and half millimeters ( i.e. 1 mm or 0.5 mm)
• The circumference of the bevel edge of the thimble is graduated into 50 divisions and marked 0 - 5 - 10 - 15.....45 - 50 in a clockwise direction
• The distance moved by the spindle during one rotation of the thimble is 0.5 mm
• Movement of one division of the thimble = 0.5 × 1/50 = 0.01 mm