GATE 2026 AR — Planning – Question 61

Data Analysis, Remote Sensing and Geo-informatics · Basic concepts in satellite remote sensing, satellites, sensors, and coverage · 2 marks · Multiple select

Which are passive remote-sensing techniques?

Sonar
Radar
Aerial photographs
Landsat imagery

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (C) Aerial photographs; (D) Landsat imagery

Explanation

Passive sensors record naturally available reflected or emitted radiation. Ordinary aerial photography and Landsat optical/thermal imagery fit this category, so C, D. Radar and sonar actively transmit a signal and measure its return, making them active sensing techniques.

More Basic concepts in satellite remote sensing, satellites, sensors, and coverage questions

GATE 2025 AR — Planning Q51 – Which spectral bands calculate NDVI?
GATE 2023 AR — Planning Q61 – Match satellite applications P cyclone monitoring, Q communication, R high-resolution…

All Basic concepts in satellite remote sensing, satellites, sensors, and coverage questions →