Which of the following wavelengths is in the infrared range of the electromagnetic spectrum?

• A. 50 nm
• B. 850 nm
• C. 400 nm
• D. 0.01 nm

Answer: (B)

Verified step by step guidance

1. Recall the general ranges of wavelengths for different regions of the electromagnetic spectrum. The infrared (IR) region typically spans wavelengths from about 700 nm to 1 mm.
2. Compare each given wavelength to the infrared range: 50 nm, 400 nm, and 0.01 nm are all much shorter than 700 nm, so they fall outside the infrared range.
3. Identify that 850 nm is greater than 700 nm and less than 1 mm, placing it within the infrared region of the spectrum.
4. Understand that wavelengths shorter than 700 nm correspond to visible light or ultraviolet, while wavelengths longer than 700 nm correspond to infrared and beyond.
5. Conclude that among the given options, 850 nm is the only wavelength that lies in the infrared range.