Least count of a micrometer
A micrometer is a screw gauge. With a pitch of 0.5 mm and 50 circular divisions the least count is 0.01 mm.
Least count
0.01mm
= 0.001 cm
0.5 mm / 50 = 0.01 mm
Least count = pitch / number of circular scale divisions.
Least count = pitch / number of circular scale divisions
A micrometer is used for the thickness of wires and sheets, to a hundredth of a millimetre. The working for the textbook numbers is 0.5 mm / 50 = 0.01 mm.
Other instruments
Micrometer: quick answers
What is the least count of a micrometer?
A micrometer is a screw gauge. With a pitch of 0.5 mm and 50 circular divisions the least count is 0.01 mm. Least count = pitch / number of circular scale divisions.
How do I find the least count of my micrometer?
Least count = pitch / number of circular scale divisions. For the instrument in front of you, read the scale and use your own numbers in the tool above.
Why does the least count matter?
The least count is the smallest reading you can make, so it sets the smallest error in a single measurement. Micrometer measures the thickness of wires and sheets, to a hundredth of a millimetre.
Is a micrometer the same as a screw gauge?
Yes. A micrometer screw gauge is the same instrument with the same rule: pitch divided by the number of circular scale divisions.