The minimum retarding means the negative potential of the anode of a photoelectric tube for which photoelectric current stops or becomes zero is called stopping potential.
Stopping potential does not depend on the intensity of incident light. On increasing intensity, the value of saturated current increases, whereas the stopping potential remains unchanged. Stopping potential does not depend on the intensity of incident radiation.
For a given intensity of radiation, the stopping potential depends on the frequency. Higher the frequency of incident light higher the value of stopping potential.