# Surveying Questions and Answers – Remote Sensing – Electromagnetic Energy

This set of Surveying Multiple Choice Questions & Answers (MCQs) focuses on “Remote Sensing – Electromagnetic Energy”.

1. Which of the following has the maximum value in an electric or magnetic field?
a) Wave length
b) Focal length
c) Frequency
d) Amplitude

Explanation: In an electromagnetic field, the electric and magnetic fields are present in the form of waves in horizontal and vertical patterns. In order to be present in that pattern, it is necessary to have maximum amplitude.

2. Velocity of light can be given as ___________
a) 1*108m/s
b) 3.9*108m/s
c) 3*108m/s
d) 3*1018m/s

Explanation: The velocity of light is generally determined by using the electro-magnetic wave principle and the plank’s law. These will help in derivation of the speed of light in vacuum, which is approximately 3*8m/s.

3. In EM waves, electric field is not used.
a) False
b) True

Explanation: The EM wave field uses both electric and magnetic fields, which will form a complex wave structure. Electric field is placed in vertical manner and magnetic field in horizontal manner.

4. Determine the wave length if the frequency is given as 67Hz.
a) 1.044*108m
b) 0.044*108m
c) 0.44*108m
d) 0.044*1010m

Explanation: We know that, λ = c /f. Where, c is the velocity of light = 3*108m/s and f is the frequency. On substitution, we get
λ = 3*108/ 67
λ = 0.044*108m.

5. Find the value of energy if the wave length is given as 43m.
a) 0.46*10-26 J
b) 0.46*10-26 J
c) 0.46*10-26 J
d) 0.46*10-26 J

Explanation: The value of energy can be given as by using plank’s relation.
Q = h*c / λ. Here, h = 6.625*10-34J.s. On substitution, we get
Q = 6.625*10-34 * 3*108 / 43
Q = 0.46*10-26 J.
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6. If the intensity of wave length decreases, the energy released will ___________
a) Increase
b) Decrease
c) Remain same
d) Zero

Explanation: The relation between wave and energy released is inversely proportional i.e., if wave length increase, energy produced by the body decrease. This can is given by the plank’s theory.

7. What will be the wave length if the energy produced is 36J?
a) 0.5*10-26m
b) 0.55*10-26m
c) 0.55*10-16m
d) 0.55*10-6m

Explanation: The value of wave length can be determined by using the energy produced by using the relation,
Q = h*c / λ. On substitution, we get
36 = 6.625*10-34 * 3*108 / λ
λ = 0.55*10-26m.

8. In an EM field, which filed is placed horizontal?
a) Gamma rays
b) Sonar field
c) Electric field
d) Magnetic field

Explanation: The EM field consists of electric and magnetic fields. Each of them plays a major role in their perspective areas. The placement of the electric and magnetic fields depends up on the intensity of wave length. Electric fields are placed in vertical manner and magnetic field in a horizontal manner.

9. The wave length sensed in remote sensing are __________
a) Nano meters and giga meters range
b) Nano meters and deci meters range
c) Nano meters and micro meters range
d) Nano meters and meters range

Explanation: In case of remote sensing, the wave lengths are expressed in nano meters and micro meters range. These are capable of recording information in a minute range.

10. In the following figure, X represents___________

a) Length
b) Time period
c) Frequency
d) Wave length

Explanation: X represents Wave length, it the calculated distance between a crest and a trough. Crest is the upper portion of the wave and trough is the lower portion of the wave.

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