RADAR works in which of the following EMR bands?

Correct option is C

The correct answer is (C) Microwave

Explanation:
• RADAR stands for Radio Detection and Ranging.
• In the context of remote sensing, RADAR is an "active" sensor, meaning it provides its own source of energy rather than relying on the sun.
• It works primarily in the Microwave region of the Electromagnetic Spectrum (EMR), with wavelengths ranging from approximately $1 millimeter$ to $1 meter$.
• Microwaves are used because they can penetrate clouds, fog, and rain, allowing RADAR to capture images during the day or night and in any weather condition (all-weather capability).

Information Booster:
• Different frequency bands within the microwave region are designated by letters, such as X-band, C-band, L-band, and P-band.
• L-band (longer wavelength) can penetrate forest canopies and some soil, while X-band (shorter) is mostly reflected by the top of the canopy.
• ISRO's RISAT (Radar Imaging Satellite) series uses microwave sensors for earth observation.

Additional Knowledge:
• Visible (Option A): Used by passive optical sensors (like our eyes or standard cameras) to capture images in the $400-700 nm$ range.
• Radiowave (Option B): While RADAR's name includes "radio," the specific high-frequency radio waves used in imaging are technically classified as microwaves.
• Infrared (Option D): Used for thermal imaging (Thermal IR) and vegetation health monitoring (Near-IR).