At what wavelength does the photopic system have the greatest sensitivity?

The photopic system, which is responsible for vision under well-lit conditions and enables the perception of color, demonstrates peak sensitivity at around 550 nm, which corresponds to the color green. This sensitivity is primarily due to the distribution of cone photoreceptors in the retina, particularly the medium-wavelength cones (M-cones) that are most responsive to light in this wavelength range.

The reason 550 nm represents the greatest sensitivity is tied to the way our visual system evolved and how it has adapted to the light conditions prevalent in our environment. The peak sensitivity at this wavelength allows humans to effectively detect and interpret the various colors present in natural daylight, enhancing survival through improved awareness of surroundings and enhanced communication via visual signals.

Other wavelengths in the choices, such as those at 400 nm (which falls into the ultraviolet and blue light range), 600 nm (yellow to orange), and 700 nm (red), do not match the optimal sensitivity of the photopic system as closely as 550 nm does. Consequently, while our eyes can detect light across a broad spectrum, the 550 nm wavelength is crucial for the most efficient functioning of the color vision system during bright lighting conditions.