Final answer:
The cis peak associated with configurational changes in molecules, such as proteins, can be detected at the wavelength of maximum absorbance (λmax) in a UV spectrum, typically within the 220-700 nm range for conjugated system chromophores.
Step-by-step explanation:
The configurational change associated with the cis peak in a UV-Vis spectrum can typically be detected at a specific wavelength known as the λmax, or the wavelength at maximal light absorbance. The precise wavelength at which a chromophore absorbs UV or visible light gives information about its electronic transitions and can be affected by the environment around the molecule, especially in the case of biochemically relevant structures such as proteins. If the chromophore is part of a molecule with conjugated systems, the absorbed wavelengths tend to be longer due to smaller energy gaps for π → π* transitions, and absorption can often be detected within the range of 220-700 nm covered by most UV spectrophotometers.