Describe the procedure of measurement of area of a irregular figure using digital planimeter
Answers
Procedure:
1. Set the scale on the tracing arm as per manufacturer’s instruction.
2. Select the position of anchor point inside or outside the figure such that tracing point reaches all positions of figure.
3. Mark the starting point on figure.
4. Place tracing point on starting point.
5. Take initial reading.
6. Move tracing point along the boundary of figure clockwise direction and note down number of times zero on dial crosses fixed index mark and also direction of crossing.
7. Continue till tracing point reaches starting point.
8. Take final reading.
9. Area of figure is given by relation:
A = M ( FR – IR ± 10 N + C)
Where A = Area
M = Multiplying constant as given by manufacturer
IR = Initial Reading
FR = Final Reading
N = Number of times zero of dial crosses fixed index mark.
C = additive constant to be added only when anchor point is inside figure.
Use + sign for clockwise and – sign for anticlockwise crossing of zero of dial.
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