In a plot of photoelectric current versus anode potential, how does
(i) the saturation current vary with anode potential for incident radiations of different frequencies but the same intensity,
(ii) the stopping potential vary for incident radiations of different intensities but the same frequency,
(iii) photoelectric current vary for different intensities but the same frequency of incident radiation? Justify your answer in each case.
(i) the saturation current vary with anode potential for incident radiations of different frequencies but the same intensity,
(ii) the stopping potential vary for incident radiations of different intensities but the same frequency,
(iii) photoelectric current vary for different intensities but the same frequency of incident radiation? Justify your answer in each case.
Answer: Saturation current set by intensity; stopping potential set by frequency.
Solution
(i) The saturation current depends only on the number of photons (the intensity), not on frequency. For the same intensity it is the same for all frequencies and does not change once all emitted electrons are collected.
(ii) The stopping potential depends only on the frequency, through . For the same frequency it is the same whatever the intensity.
(iii) The saturation photocurrent increases in proportion to the intensity, because more photons eject more electrons.
(ii) The stopping potential depends only on the frequency, through . For the same frequency it is the same whatever the intensity.
(iii) The saturation photocurrent increases in proportion to the intensity, because more photons eject more electrons.
CBSE Class 12 Board · 2007 · Delhi · Subjective