Which of the following phenomena is called photoelectric effect?

The phenomenon called photoelectric effect is when a metal absorbs quanta of light and then emits electrons. This means that when light shines on a metal, the energy from the light is absorbed by the metal atoms, which causes electrons to be emitted from the metal surface. This effect is important in many technologies such as solar cells and photo detectors. The other options are not examples of the photoelectric effect. The first option describes the reverse effect, where high energy electrons cause the emission of photons, which is known as the Bremsstrahlung effect. The second option describes the process of photon emission through the release of energy by a particle as it slows down, which is known as the Cerenkov radiation. The third option describes a similar effect to the photoelectric effect, but instead of emitting electrons, the metal would emit light, which is known as the photoluminescence effect. Finally, the fourth option describes the process of photon absorption, which is not related to the photoelectric effect.