(a) What frequency of light is needed to produce electrons of kinetic energy 3.00 eV from illumination of lithium? (b) Find the wavelength of this light and discuss where it is in the electromagnetic spectrum.
Strategy We have enough information to determine the photon energy needed from Equation (3.30), and we can determine the frequency from E = hf.
h f=\phi+\frac{1}{2} m v_{\max }^{2} (3.30)