When a photoelectric effect experiment was carried out using a metal “M” and light at wavelength λ₁, electrons with a kinetic energy of 1.6 × 10^-19 J were emitted. The wavelength was reduced to one-half its original value and the experiment was repeated (still using the same metal target). This time electrons with a kinetic energy of 6.4 × 10^-19 J were emitted. Find the electron binding energy for metal M. (The actual wavelengths used were not recorded, but it is still possible to find the binding energy.)