A Level Physics Practice Exam

What does the work function equation relate to?

1. The energy of emitted photons

2. The energy needed to remove an electron from an atom

3. The frequency of light

4. The total energy of a wave

The correct answer is: The energy needed to remove an electron from an atom

The work function equation is fundamentally related to the energy required to remove an electron from the surface of a material, typically a metal. This concept is rooted in the photoelectric effect, where light photons incident on a material can provide enough energy to dislodge electrons, but only if the energy of the incoming photons meets or exceeds this work function. The work function is denoted by the symbol φ (phi) and is expressed in electron volts (eV). It represents the minimum energy that an electron within the material requires to overcome the attractive forces binding it to the nucleus and escape into free space. If the energy of the incoming photon (which is quantized and proportional to its frequency) is greater than the work function, the excess energy contributes to the kinetic energy of the emitted electron. Understanding this connection is essential for interpreting various phenomena in quantum physics, such as the threshold frequency below which no electrons are emitted regardless of the intensity of the light. Thus, it directly ties into the physics of electron emission and the interaction between light and matter.