EDM Instruments Types Questions and Answers

This set of Surveying Multiple Choice Questions & Answers (MCQs) focuses on “Types of EDM Instruments”.

1. Different types of EDM’s are obtained on the basis of__________
a) Wave length
b) Carrier wave
c) Frequency
d) Time period
View Answer

Answer: b
Explanation: EDM instruments can be classified based on the type of carrier wave employed. The classification includes microwave, Infra-red, visible light instruments. It can be observed that all three categories of EDM instruments use short wavelengths and hence higher frequencies.

2. Which among the following EDM instruments is having more range?
a) Infra-red instruments
b) Visible light instruments
c) Microwave instruments
d) Gamma ray instruments
View Answer

Answer: c
Explanation: The frequency range of the microwave instrument is about 3-30 kHz which provides it the ability to cover a range up to 100km. The usage of gamma rays is not possible in the case of Total station.

3. Which type of modulation is used in the case of microwave instrument?
a) Frequency modulation
b) Amplitude modulation
c) Carrier wave modulation
d) Time period modulation
View Answer

Answer: a
Explanation: Frequency modulation is used in all kinds of EDM instruments which make it feasible, but, amplitude modulation is also used in remaining classifications which makes it quite different from the microwave instruments.

4. The frequency range used in visible light instruments is______________
a) 5*10¹¹ Hz
b) 5*10⁸ Hz
c) 5*10¹⁰ Hz
d) 5*10¹⁴ Hz
View Answer

Answer: d
Explanation: The frequency range in the visible light instruments is capable of determining the range of its calculation which may affect it.

5. Geodimeter uses which of the following waves as a carrier wave?
a) Microwaves
b) Visible light
c) Infra-red
d) Cosmic rays
View Answer

Answer: b
Explanation: Geodimeter is a classification of EDM based on carrier wave. This instrument uses visible light as its source and possesses a range of 25 km, having accuracy up to 2-3km.

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6. Microwave EDM instrument requires two instrument stations.
a) True
b) False
View Answer

Answer: a
Explanation: Visible light EDM instrument requires only one instrument station whereas the microwave EDM instrument requires two instrument stations which make it quite expensive and accurate as it can cover long distances.

7. What among the following indicates the range of Geodimeter?
a) 20 km
b) 30 km
c) 25km
d) 35 km
View Answer

Answer: c
Explanation: Geodimeter uses visible light as a carrier wave in which it is capable of obtaining information, like the distance between the points, within 25km of range.

8. The wavelength of I.R in infra-red instruments is about___________
a) 0.6 * 10^-6 m
b) 1.0 * 10^-6 m
c) 0.7 * 10^-6 m
d) 0.9 * 10^-6 m
View Answer

Answer: d
Explanation: Infra-red instruments use infra-red waves as carrier waves. These are widely used in the present day as these are able to provide information with less economy.

9. Frequency modulation is used in the case of visible light EDM.
a) True
b) False
View Answer

Answer: b
Explanation: Though frequency modulation is used in all the EDM instruments, the usage of amplitude modulation is more in case of visible light EDM instrument, which is capable of keeping frequency constant and measure the wavelength for calculation phase difference.

10. Which among the following EDM instruments are capable of producing output with less expenditure?
a) Microwave instruments
b) Cosmic ray instruments
c) Visible light instruments
d) Infra-red instruments
View Answer

Answer: d
Explanation: Infra-red instruments use Gallium-Arsenide diode as a source for obtaining infra-red waves. These diodes can be easily directed to amplitude modulation at high frequencies. So, infra-red carrier wave is obtained by an inexpensive method, which makes the entire process inexpensive.

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