Question
For a photosensitive surface, threshold wavelength is $\lambda_0.$ Does photoemission occur if the wavelength of radiation is (i) more than $\lambda_0$ and (ii) less than $\lambda_0?$ Justify your answer.
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Answer
Energy of a photon $\text{E}=\frac{\text{hc}}{\lambda}$ For emission of photoelectrons energy of a photon $\geq$ work function or wavelength of incident photon $\lambda$ should be less than threshold wavelength $\lambda_0(\text{i.e., }\lambda<\lambda_0).$
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