Question

What is least count of an instrument?

(a) The lowest value that can be measured accurately

(b) The greatest value that can be measured accurately

(c) Half of the lowest value that can be measured accurately

(d) Mean of the lowest and highest values

The question was posed to me in an international level competition.

This key question is from Accuracy, Precision of Instruments and Errors in Measurement topic in section Units and Measurements of Physics – Class 11

Answer 1

Right answer is (a) The lowest value that can be measured accurately

To explain I would say: The least count of an instrument is the lowest value that can be measured accurately. For example, if the lowest value that can be measured by a ruler is 1 mm, then the least count is 1 mm.