Least count of a spherometer
The pitch is 0.1 cm and the circular scale has 100 divisions, so the least count is 0.001 cm.
Least count
0.001cm
0.1 cm / 100 = 0.001 cm
Least count = pitch / number of circular scale divisions.
Least count = pitch / number of circular scale divisions
A spherometer is used for the radius of curvature of a lens or a mirror, and the thickness of thin plates. The working for the textbook numbers is 0.1 cm / 100 = 0.001 cm.
Other instruments
Spherometer: quick answers
What is the least count of a spherometer?
The pitch is 0.1 cm and the circular scale has 100 divisions, so the least count is 0.001 cm. Least count = pitch / number of circular scale divisions.
How do I find the least count of my spherometer?
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. Spherometer measures the radius of curvature of a lens or a mirror, and the thickness of thin plates.