A planimeter is an instrument used for
- Achecking whether a given surface is plane
- Bchecking whether the plane table surface is level
- Cfinding area plans and mapsCorrect
- Dfinding the slope of a given terrain
Solution
Concept
Function of planimeter in area measurement
Formula
NONE
Step-by-step solution
1. A planimeter is a mechanical or digital instrument used in surveying and drafting. 2. It measures the surface area of two-dimensional closed figures directly on plans, drawings, or maps. Answer: C
Explanation
A planimeter is a precise mechanical or electronic measuring instrument designed specifically for determining the area of two-dimensional, irregular shapes on paper, maps, or engineering drawings. By tracing the perimeter of a closed boundary with its tracing arm, the instrument integrates the boundary coordinates to calculate the enclosed area. Therefore, option C correctly identifies its primary function.
Why the other options are wrong
A) Planimeters do not test or check the planarity of surfaces. B) Spirit levels are used for levelling plane tables, not planimeters. D) Clinometers measure slopes, not planimeters.
Shortcut
Planimeter = PLAN-area calculator for maps and drawings.
Common mistake
Selecting option A or B by mistaking a planimeter for a tool used to check surface level or flatness instead of measuring map area.
Correct answer: C) finding area plans and maps