In the photoelectric effect, the stopping potential is the voltage that

  • A. just prevents the most energetic photoelectrons from reaching the collector
  • B. starts the emission of electrons
  • C. doubles the photocurrent
  • D. equals the work function in volts

Explanation

Applying a retarding voltage reduces the photocurrent, and the value that cuts it to zero measures the maximum kinetic energy directly, since that energy equals the electronic charge multiplied by the stopping potential. The stopping potential depends on frequency but not on intensity. Plotting it against frequency is the classic experiment for finding Planck's constant.

Related questions