Question

In remote sensing, the order of the wavelength bands of electromagnetic radiation used for data acquisition is

• A. Visible < Near Infrared < Thermal Infrared < Microwave
• B. Thermal Infrared < Near Infrared < Visible < Microwave
• C. Microwave < Near Infrared < Thermal Infrared < Visible
• D. Near Infrared < Thermal Infrared < Microwave < Visible

Hint:

Recall the approximate wavelength range of each band, visible, near infrared, thermal infrared and microwave, and arrange them from shortest to longest.

Answer 1

The Correct Option is A

Step 1: Understanding the Question.
Remote sensing instruments collect electromagnetic energy from different parts of the spectrum, and each band is defined by its wavelength. The question asks us to arrange the visible, near infrared, thermal infrared and microwave bands in order of increasing wavelength.

Step 2: Key Formula or Approach.
Every named band in remote sensing has a standard wavelength range: visible light runs from about \(0.4\) to \(0.7\) micrometres, near infrared from about \(0.7\) to \(1.3\) micrometres, thermal infrared from about \(3\) to \(14\) micrometres, and microwave from about \(1\) millimetre to \(1\) metre, thousands of times longer than thermal infrared. Arranging the bands from shortest to longest wavelength gives the correct order.

Step 3: Detailed Explanation.
Starting from the shortest wavelength, visible light comes first since our eyes and most cameras use this narrow band.
Next comes near infrared, just beyond red light, still measured in a fraction of a micrometre.
After that comes thermal infrared, tied to heat radiated by objects, which sits at a much longer wavelength, several micrometres.
Microwave radiation comes last, with wavelengths in the millimetre to metre range, far longer than any of the other three bands, which is why radar and passive microwave sensors can see through cloud and haze that block the shorter bands.
Option (A) Visible \(<\) Near Infrared \(<\) Thermal Infrared \(<\) Microwave follows exactly this shortest to longest order.
Option (B) puts thermal infrared before near infrared and visible, which is backwards since thermal infrared has a longer wavelength than both.
Option (C) starts with microwave, the longest wavelength band of all, so this sequence runs from longest to shortest, the reverse of what is asked.
Option (D) places visible, the shortest band, at the very end, which is also backwards.

Step 4: Final Answer.
Ordered from shortest to longest wavelength, the sequence is Visible, then Near Infrared, then Thermal Infrared, then Microwave.
This corresponds to option (A).