Q.87
Read the following statements and
choose the correct answer from the options given below
(A). Photographic camera is an active sensor when used in sunlight.
(B). Photographic camera is a passive sensor when used in sunlight
(C). Radar and laser altimeter are active sensors
(D). Passive sensors are preferable when natural emittance or reflectance levels are low.
EXPLANATION
Moisture and Temperature Soil Regimes, Land Capability & Fertility Capability Classification (FCC)
- Statement (A) is incorrect & (B) is correct: In sunlight, a photographic camera utilizes the sun as an external natural radiation source to record reflected energy, making it a passive sensor.
- Statement (C) is correct: Radar (radio waves) and LiDAR/laser altimeters generate their own artificial beam of electromagnetic radiation and detect the returned backscatter, classifying them as active sensors.
- Statement (D) is incorrect: When natural ambient reflectance/emittance levels are low (e.g. at night or under thick clouds), active sensors are required because passive sensors cannot operate without sufficient ambient illumination.
- Conclusion: Statements (B) and (C) only are correct. (Correct answer: Option 1)
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