Least Count of Theodolite

Least count of theodolite is 20 seconds.

Solution

Least count of an instrument is minimum reading that can be measured by instrument. Accuracy is more for instruments having less value of least count.

Instrument	Least Count
Total station	1 Second
Theodolite	20 Second
Prismatic compass	30 Minute
Surveyors compass	15 Minute

Total station and theodolite are used to measure horizontal angles as well as vertical angles in a plane.

Prismatic compass and surveyors compass are used to measure only horizontal angles. Angles may be affected by local attraction. Hence, least count of theodolite is 20 seconds.

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