Which region contains wavelengths shorter than 400 nm?

Which region contains wavelengths shorter than 400 nm?

• A. UV
• B. Infrared
• C. Visible light
• D. Microwave

Answer: (A)

Wavelengths and the electromagnetic spectrum are organized by wavelength, with 400 nanometers marking the lower end of the visible range. Wavelengths shorter than 400 nm fall into ultraviolet because ultraviolet lies beyond the violet end of visible light. The visible region is roughly 400–700 nm, infrared spans about 700 nm to 1 mm, and microwaves are longer still, from millimeters to centimeters. So wavelengths shorter than 400 nm belong to ultraviolet.

Wavelengths and the electromagnetic spectrum are organized by wavelength, with 400 nanometers marking the lower end of the visible range. Wavelengths shorter than 400 nm fall into ultraviolet because ultraviolet lies beyond the violet end of visible light. The visible region is roughly 400–700 nm, infrared spans about 700 nm to 1 mm, and microwaves are longer still, from millimeters to centimeters. So wavelengths shorter than 400 nm belong to ultraviolet.