Fill in the blank(s) with the correct answer: _ EDMs can be used up to a range of 100 km while type is used with a range up to 3 km.

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answered Feb 26, 2022 by ManasOdak (110k points)
selected Feb 26, 2022 by Dineshraikar

Best answer

Correct Answer - Option 4 : Microwave, infrared

Concept:

Types of EDM Instruments:

Depending on the types of carrier wave employed, EDM instruments can be classified under the following three heads :

1. Microwave Instruments:

These instruments make use of microwaves. Such instruments were invented as early as 1950 in South Africa by Dr. T.L. Wadley and named them as Tellurometers.
The instrument needs only 12 to 24 V batteries. Hence they are light and highly portable.
Tellurometers can be used in day as well as in night.
The range of these instruments is up to 100 km.

2. Infrared Wave Instruments:

In this instrument amplitude modulated infrared waves are used. Prism reflectors are used at the end of line to be measured.
These instruments are light and economical and can be mounted on theodolite. With these instruments accuracy achieved is ± 10 mm.
The range of these instruments is up to 3 km.

3. Visible Light Wave Instruments:

These instruments rely on propagation of modulated light waves. This type of instrument was first developed in Sweden and was named as Geodimeter.
During night its range is up to 2.5 km while in day its range is up to 3 km.