Certain sun glasses having small crystals of incorporated in the lenses

CHEMISTRY · Subjective · CBSE · Chemistry · Structure of Atom · Structure of Atom

Problem

Certain sun glasses having small crystals of

\text{AgCl}

incorporated in the lenses, on exposure to light of appropriate wavelength turns to gray colour to reduce the glare following the reaction:

\text{AgCl} \xrightarrow{h\nu} \text{Ag} + \text{Cl} \quad (\text{Gray})

If the heat of reaction for the decomposition of

\text{AgCl}

248 \text{ k J mol}^{-1}

, what maximum wavelength is needed to induce the desired process?