Especially for Polytechnic Students

1. Unit 6: Measurement of Area and Volume
6.1 Digital Planimeter: Components uses of Digital Planimeter:
mponempone
Components:
1) Roller
2) Tracing Arm
3) Tracing Magnifier
4) Tracing Point
5) Function Keys
6) Display
Prepared by- Abhay Abhale

2. Unit 6: Measurement of Area and Volume
6.1 Digital Planimeter: Components uses of Digital Planimeter:
Function Keys:
i. ON – To on the instrument, to start the measurement.
ii. OFF – To off the after the measurement is over.
iii. START - To start the tracing on area boundary.
iv. UNIT-1 – To set unit of area in vertical direction.
v. UNIT-2 - To set unit of area in vertical direction.
vi. Scale – To set the scale as per scale of map to be trace.
vii. AVER – To find cumulative average to get better
accuracy
viii.MEMO – To Temporary store traced area inside the
Planimeter.
ix. HOLD – To hold the reading , so that after movement
of tracing magnifier reading will not be counted.
x. 0-9 NUMBER KEYS – To give input for scale etc.
Roller
Tracing Magnifier
Display
Function Keys
Tracing Arm
Prepared by- Abhay Abhale

3. Unit 6: Measurement of Area and Volume
6.2 Measurement of area using digital Planimeter:
i. Keep the drawing sheet on level horizontal surface.
ii. Press ON key and display indicate zero 'O‘.
iii. Select the scale by pressing, 'SCALE key.
iv. Press the unit key and select the unit.
v. Mark the starting point on outline of area.
vi. Set the tracing point of magnifying circle on starting point.
vii. Press 'START' key and display with 'O' and beep sound.
viii. Move the tracer clockwise along the outline or periphery of the area.
ix. After completing one rotation the tracing point comes against starting point
press ‘HOLD' key and observe the reading on display.
x. This will gives area on the display.
xi. For better accuracy press ‘AVER’ then ‘HOLD’ and again start tracing from
starting point.
xii. For larger area divide it into number of sub-areas and take measurement of
each area an add it.
Prepared by- Abhay Abhale

4. Unit 6: Measurement of Area and Volume
6.3 Measurement of volume of reservoir from contour map.
i. Computation of Volume Prizmoidal Formula Volume,
V= L/3 x [ A1 + An + 2 (A3 + A5+ ….. An-2) + 4 (A2 + A4 + An-1) ]
i.e. Volume = Common Distance/3 x [ Area of First Section + Area of Last Section + 2
(Sum of Area of Odd Sections) + 4 (Sum of areas of even Section) ]
In short,
Prepared by- Abhay Abhale

5. Unit 6: Measurement of Area and Volume
6.3 Measurement of volume of reservoir from contour map.
i. Computation of Volume Trapezoidal Rule (Average End Area Rule)
Volume (Cutting or Filling)
V= d/2 [ A1 + An + 2 (A2 + A3 + …….An-1)
i.e. Volume= Common Distance/2 [ First section area + Last section area + 2 (
sum of areas of other sections)
In short,
Prepared by- Abhay Abhale

6. Unit 6: Measurement of Area and Volume
6.3 Simple Numerical
Problem
(*Not in syllabus)
A1 A3A2 A4 A5
Prepared by- Abhay Abhale