Light of wavelength 600 nm is incident on potassium (work function 2.3 eV ). Will photoemission of electrons occur? What is the longest wavelength…

$$E = \frac{hc}{\lambda}$$$$= \frac{1240\,eV\,nm}{600\,nm}$$$$= 2.06\,eV$$$\displaystyle \because$ Work function $\displaystyle \phi_0 = 2.3\,eV$$\displaystyle \because E < \phi_0$ No emission will take place.$$\lambda_{\max} = \frac{hc}{\phi}$$$$= \frac{1240\,eV\,nm}{2.3\,eV}$$$$\lambda_{\max} = 539.13\,nm$$