The surface of a certain metal is first illuminated with light of wavelength \(\lambda_1=350\,\text{nm}\), and then by light of wavelength \(\lambda_2=540\,\text{nm}\). It is found that the maximum speed of the photoelectrons in the two cases differ by a factor of \(2\). The work function of the metal (in eV) is close to
\[
\left(\text{Energy of photon}=\frac{1240}{\lambda(\text{nm})}\text{ eV}\right)
\]