A Level Physics Practice Exam

What is the primary outcome of the photoelectric effect?

1. The emission of photons from the surface

2. The absorption of electrons

3. The transformation of light into thermal energy

4. The ejection of electrons from a material

The correct answer is: The ejection of electrons from a material

The primary outcome of the photoelectric effect is the ejection of electrons from a material when it is exposed to light of sufficient energy. In this phenomenon, photons from the incident light strike electrons in the material, providing them with enough energy to overcome the work function—the minimum energy required to liberate an electron from the surface of the material. If the energy of the incoming photons exceeds this threshold, the electrons are emitted from the surface, resulting in an observable current if the setup allows for it. This effect was crucial in demonstrating the particle-like behavior of light and contributed to the development of quantum mechanics, as it highlighted the quantized nature of electromagnetic radiation. The emission of photons is not part of the photoelectric effect itself; rather, the process involves the interaction between photons and electrons within the material. Thus, the correct choice focuses on the role of electrons and their liberation as the main outcome of this physical phenomenon.