Answer
Ultraviolet light has more energy per photon.
Work Step by Step
The ejection of an electron depends on the interaction of one photon with an electron.
For photons, E = hf, where E is the energy, h is Planck's constant, and f is the photon's vibrational frequency. UV light has a higher frequency than visible light, so ultraviolet photons are more effective at inducing the photoelectric effect.
This is discussed on pages 585-587.
