Stopping Potential

Definition

Stopping potential is the minimum potential difference required to just prevent the emission of photoelectrons from a metal surface when it is illuminated by light. It is a key concept in understanding the photoelectric effect and the particle-wave duality of light.

5 Must Know Facts For Your Next Test

1. The stopping potential is directly proportional to the work function of the metal and inversely proportional to the frequency of the incident light.
2. Stopping potential is measured by applying a reverse potential difference between the illuminated metal surface and a collector electrode until the photoelectric current is just reduced to zero.
3. The stopping potential does not depend on the intensity of the incident light, only on its frequency, as per the photoelectric effect.
4. The stopping potential is used to determine the maximum kinetic energy of the emitted photoelectrons, which is equal to the difference between the photon energy and the work function of the metal.
5. The concept of stopping potential is crucial in demonstrating the particle-like nature of light, as it shows that light transfers its energy to electrons in discrete quanta, rather than continuously.

Review Questions

• Explain how the stopping potential is related to the photoelectric effect and the work function of a metal.
  • The stopping potential is the minimum potential difference required to just prevent the emission of photoelectrons from a metal surface when it is illuminated by light. It is directly proportional to the work function of the metal, which is the minimum energy required to remove an electron from the metal's surface. The stopping potential is used to determine the maximum kinetic energy of the emitted photoelectrons, which is equal to the difference between the photon energy and the work function of the metal. This relationship is a key feature of the photoelectric effect and demonstrates the particle-like nature of light.
• Describe how the stopping potential is measured and how it is used to understand the particle-wave duality of light.
  • The stopping potential is measured by applying a reverse potential difference between the illuminated metal surface and a collector electrode until the photoelectric current is just reduced to zero. This stopping potential is directly proportional to the maximum kinetic energy of the emitted photoelectrons. The concept of stopping potential is crucial in demonstrating the particle-like nature of light, as it shows that light transfers its energy to electrons in discrete quanta, rather than continuously. This provides evidence for the particle-wave duality of light, where light exhibits both wave-like and particle-like properties.
• Analyze the relationship between the stopping potential, the frequency of the incident light, and the work function of the metal in the context of the photoelectric effect.
  • The stopping potential is inversely proportional to the frequency of the incident light and directly proportional to the work function of the metal in the photoelectric effect. This relationship is described by the equation $V_s = \frac{h \cdot f - \phi}{e}$, where $V_s$ is the stopping potential, $h$ is Planck's constant, $f$ is the frequency of the incident light, $\phi$ is the work function of the metal, and $e$ is the charge of an electron. This equation demonstrates that the stopping potential depends on the energy of the incident photons (frequency) and the energy required to remove an electron from the metal (work function), which are key principles of the photoelectric effect. Understanding this relationship is crucial for analyzing the particle-like nature of light.

Related terms

Photoelectric Effect: The phenomenon where electrons are emitted from a metal surface when it is illuminated by light of sufficient energy.

Work Function: The minimum energy required to remove an electron from a metal surface, which is characteristic of the metal.

Kinetic Energy: The energy an object possesses due to its motion, which in the photoelectric effect is the energy of the emitted photoelectrons.