Stopping potential

Definition

Stopping potential refers to the minimum voltage needed to halt the flow of photoelectrons emitted from a material when exposed to light. This concept is crucial in understanding the energy balance in processes like the photoelectric effect and Compton scattering, where photons interact with matter, causing electrons to be emitted or scattered. It highlights the relationship between the energy of incoming photons and the work function of materials, providing insights into how energy is transferred during these interactions.

5 Must Know Facts For Your Next Test

1. The stopping potential is directly related to the kinetic energy of the emitted photoelectrons, as it needs to equal the maximum kinetic energy for complete cessation of their motion.
2. In experiments, measuring the stopping potential allows for the calculation of the work function of the material by using the equation: $$eV_s = E_{photon} - \phi$$, where $$V_s$$ is stopping potential, $$E_{photon}$$ is photon energy, and $$\phi$$ is work function.
3. Stopping potential demonstrates that not all photons will cause electron emission; only those with sufficient energy above the work function can do so.
4. In Compton scattering, stopping potential can be affected by changes in electron energy as it reflects shifts in momentum during photon-electron interactions.
5. By analyzing stopping potential in various materials, scientists can gain insight into their electronic properties and how they respond to different wavelengths of light.

Review Questions

• How does stopping potential relate to the photoelectric effect and what role does it play in determining whether electrons are emitted?
  • Stopping potential is critical in the context of the photoelectric effect because it represents the minimum voltage required to stop emitted electrons. When light strikes a material, if its photons have enough energy to overcome the work function, electrons will be ejected. The stopping potential allows us to measure this process by indicating how much kinetic energy these emitted electrons possess, linking photon energy with electron behavior.
• Discuss how stopping potential can be utilized to determine a material's work function through experimental measurements.
  • Stopping potential provides a practical way to determine a material's work function by using its relationship with photon energy. In an experiment, by applying varying voltages and identifying the point at which no electrons reach the detector, we can calculate the stopping potential. By using the equation $$eV_s = E_{photon} - \phi$$, we can rearrange it to find the work function ($$\phi$$) if we know the stopping potential and incoming photon energy.
• Evaluate how variations in stopping potential can inform scientists about the electronic properties of different materials during experiments involving Compton scattering.
  • Variations in stopping potential during experiments involving Compton scattering can reveal essential information about a material's electronic properties. Changes in stopping potential indicate differences in how electrons interact with incoming photons, suggesting variations in binding energies or electronic configurations within the material. Analyzing these differences helps scientists understand how different materials respond to light across various wavelengths and their efficiency in converting photon energy into kinetic energy of emitted electrons.

Related terms

photoelectric effect: The phenomenon where electrons are ejected from a material upon absorption of light or electromagnetic radiation.

photon energy: The energy carried by a single photon, which is directly proportional to its frequency and inversely proportional to its wavelength.

work function: The minimum energy required to remove an electron from the surface of a material, playing a key role in photoemission processes.