For which one of the following is planimeter used ?

A planimeter, also known as a platometer, is a specialized surveying instrument used primarily to determine the area of a two-dimensional shape or irregular region on a map [t1, t7]. It functions by tracing the perimeter of the area with a tracer arm, which then transfers the movement to a scale or measuring wheel that indicates the total area in square units [t2]. This tool is indispensable in fields like civil engineering, cartography, and architecture for calculating land areas from maps or plans where boundaries are not straight lines [t4, t6]. While modern digital versions and GPS-based applications can also measure distances and perimeters, the fundamental purpose of a planimeter in traditional surveying and map work is the precise measurement of surface area [t8, t9]. Other map components like distance and direction are typically handled by scales and compasses respectively [c3].

Sources

1. [1] Exploring Society:India and Beyond. Social Science-Class VI . NCERT(Revised ed 2025) > Chapter 1: Locating Places on the Earth > Before we move on ... > p. 23