What are the additive and multiplying constants of planimeter?
Area of the irregular figure measured by planimeter is given by:
Where M = Multiplying constant
C = Additive costant
Multiplying Constant: It is the multiplier whose value is marked on tracing arm next to the scale division (the number of units of area per revolution of the roller or wheel).
It can be obtained by length of tracing arm x circumference of the wheel. Generally it is taken as 100.
Additive Costant: It is the constant given in the table provided by the manufacturer. It is taken in to consideration only when anchor point is inside the figure, else it is zero.