A Level Physics Practice Exam

What particles are ejected from an atom due to the photoelectric effect?

1. Protons

2. Electrons

3. Neutrons

4. Photons

The correct answer is: Electrons

The photoelectric effect describes the phenomenon where electrons are ejected from a material, typically a metal, when it is exposed to light or other electromagnetic radiation of sufficiently high frequency. When photons (light particles) strike the surface of the material, they can transfer their energy to electrons. If the energy of the incoming photon exceeds the work function—the minimum energy needed to remove an electron from the surface—then the electron can escape the attractive forces of the nucleus. This process illustrates the particle nature of light and shows that light can impart energy to electrons, causing them to be released from their atomic bind. The emitted particles in this scenario are specifically electrons, which are negatively charged and represent the particles that experience this ejection. Photons, although involved in the process, do not constitute the particles that are ejected from the atom. Instead, they serve as the incident energy that facilitates the ejection of electrons. Protons and neutrons, being nucleons located within the nucleus of the atom, are not involved in the photoelectric effect at all, as their binding and structure are fundamentally different from that of electrons. Thus, the dynamic of the photoelectric effect focuses specifically on the interaction between photons and electrons, solidifying the understanding that electrons are the particles