Which wavelength range corresponds to visible lasers?

Which wavelength range corresponds to visible lasers?

• A. 1400 to 700 nm
• B. 700 to 400 nm
• C. 400 to 200 nm
• D. 200 to 50 nm

Answer: (B)

Visible lasers emit light that humans can see, which lies in a window roughly from 400 to 700 nanometers. Describing the range as 700 to 400 nm covers that same interval, just listed in reverse order, so it matches the visible spectrum. The other ranges fall outside visible light—shorter wavelengths are ultraviolet and longer wavelengths are infrared—so they aren’t visible lasers.

Visible lasers emit light that humans can see, which lies in a window roughly from 400 to 700 nanometers. Describing the range as 700 to 400 nm covers that same interval, just listed in reverse order, so it matches the visible spectrum. The other ranges fall outside visible light—shorter wavelengths are ultraviolet and longer wavelengths are infrared—so they aren’t visible lasers.