Final answer:
Doubling the frequency of incident radiation while keeping intensity constant in a photocell does not change the photoelectric current but increases the kinetic energy of the photoelectrons.
Step-by-step explanation:
When considering the effects of doubling the frequency of incident radiation on a photocell while keeping the intensity constant, we must look at both the photoelectric current and the kinetic energy of the photoelectrons. First, the photoelectric current will not change as it is dependent on the intensity of the light, which in this case remains constant. The number of photons hitting the surface per unit time remains the same, so the number of photoelectrons and the resulting current also remains the same.
Second, the kinetic energy of the photoelectrons will increase. This is because the kinetic energy of photoelectrons is given by the equation KE = hf - BE, where h is Planck's constant, f is the frequency of the light, and BE is the binding energy of the electron in the metal. When the frequency is doubled, the term hf becomes significantly larger, leading to an increase in the kinetic energy of the emitted photoelectrons, provided the frequency is above the threshold frequency.