A point source of light produces photoelectrons from a photo cell with certain velocity. Which of the following is correct for the photoelectrons if the distance between the photo cell and the source of light is increased?
Choose one answer.
a. Velocity will increase.
b. Velocity will decrease.
c. Velocity will remain the same.
d. Number of photo electrons will increase.
Answer = c.
To determine the correct answer, let's analyze the scenario.
When a point source of light produces photoelectrons in a photo cell, the photoelectrons acquire their velocity due to the energy received from the photons of light. The energy of a photon is directly related to the frequency (or inversely related to the wavelength) of the light.
Now, if the distance between the photo cell and the source of light is increased, the intensity of the light reaching the photo cell decreases. As a result, fewer photons are incident on the photo cell.
Since the number of photons reaching the photo cell decreases, the number of photoelectrons emitted may also decrease. In this case, the correct answer is (d) Number of photoelectrons will increase.
It's important to note that the velocity of the photoelectrons may remain the same, assuming the frequency (or energy) of the incident light remains constant. However, the question only asks about the number of photoelectrons, not their velocity.