American Board of Opticianry (ABO) Practice Test

Between which two wavelengths in the visible spectrum does the blue portion of light lie according to the text?

1. 450 nm to 495 nm

2. 400 nm to 440 nm

3. 500 nm to 550 nm

4. 550 nm to 600 nm

The correct answer is: 450 nm to 495 nm

Blue light has a wavelength range of approximately 450 nm to 495 nm, which falls between ultraviolet and green light. The other options are incorrect because they either include wavelengths outside of the visible spectrum (ultraviolet or green light) or they do not capture the entire range of the blue portion of light. For example, option B only includes half of the range while options C and D include wavelengths outside of the blue portion. Therefore, option A is the only correct range for the blue portion of light in the visible spectrum.