The ejection of an electron depends on the interaction of one photon with an electron. Photons of violet light are more energetic than red photons.
Work Step by Step
For photons, E = hf, where E is the energy, h is Planck's constant, and f is the photon's vibrational frequency. Violet light has a higher frequency than red light. Because only one photon is needed to eject an electron and give it energy, an intense red light gives less energy to ejected electrons than a weak violet light does. This is discussed on pages 585-587.