What is infrared spectrum range?

• A. 700 to 1400 nm
• B. 1400 to 700 nm
• C. 4000 to 700 nm
• D. 1800 to 2600 nm

Answer: (B)

Infrared light occupies wavelengths longer than visible light, starting around 700 nanometers and extending into the micrometer range. A common portion of this region is near-infrared, roughly from 700 to 1400 nanometers. Saying the range as 1400 to 700 nanometers is just the same interval written in reverse order; it still lies entirely in the infrared. This interval sits right after the visible boundary and is a standard way to refer to part of the infrared spectrum used in many applications like IR spectroscopy and near-infrared detectors. The other options either include visible wavelengths or describe only a narrower slice of infrared.