Question

What is the meaning of stopping potential in photoelectric effect?

Hint:

The stopping potential is used to measure the kinetic energy of photoelectrons emitted in the photoelectric effect. It is the minimum potential required to stop the most energetic photoelectrons from reaching the anode. This potential is crucial in verifying Einstein's photoelectric equation.

Answer 1

The stopping potential in the photoelectric effect is the minimum negative potential that must be applied to the anode to stop the most energetic photoelectrons from reaching it. When monochromatic light strikes a material, photoelectrons are emitted due to the energy transferred from the photons of light. These electrons are emitted with a certain kinetic energy, which depends on the frequency of the incident light and the work function of the material.
To stop the photoelectrons from reaching the anode, a negative potential (stopping potential) is applied. The stopping potential is the voltage required to reduce the kinetic energy of the emitted electrons to zero. It essentially counters the kinetic energy of the fastest electrons, halting their motion. The relation between the kinetic energy of the emitted photoelectron \( E_k \) and the stopping potential \( V_0 \) is: \[ E_k = eV_0, \] where: - \( E_k \) is the kinetic energy of the photoelectron,
- \( e \) is the charge of the electron,
- \( V_0 \) is the stopping potential. Thus, the stopping potential is a measure of the maximum kinetic energy of the emitted photoelectrons. The photoelectric effect demonstrates that light behaves as particles (photons), as only photons with energy greater than the material's work function can release electrons.