Two different monochromatic light sources, one yellow (580 nm) and one violet (425 nm), are used in a photoelectric effect experiment. The metal surface has a photoelectric threshold frequency of 6.20 × 1014 Hz.
(a) Are both sources able to eject photoelectrons from the metal? Explain.
(b) How much energy is required to eject an electron from the metal?
(Use h = 4.136×10−15 eV·s.)