Wavelengths are measured in which unit?

Wavelengths are measured in which unit?

• A. Nanometers
• B. Kilometers
• C. Inches
• D. Feet

Answer: (A)

Wavelengths describe the spacing between peaks of a light wave, and for visible and near-infrared light used in lasers, that distance is extremely small. Nanometers are used because a nanometer is one billionth of a meter, which matches the scale of typical laser wavelengths (about 400–1100 nm). Kilometers, inches, and feet are far too large to describe a light wave. So the correct unit is nanometers, which is why laser wavelengths for hair removal are specified in nanometers (e.g., 755 nm, 810 nm, 1064 nm).

Wavelengths describe the spacing between peaks of a light wave, and for visible and near-infrared light used in lasers, that distance is extremely small. Nanometers are used because a nanometer is one billionth of a meter, which matches the scale of typical laser wavelengths (about 400–1100 nm). Kilometers, inches, and feet are far too large to describe a light wave. So the correct unit is nanometers, which is why laser wavelengths for hair removal are specified in nanometers (e.g., 755 nm, 810 nm, 1064 nm).