Modern Physics 2 Question 5
5. When a certain photosensitive surface is illuminated with monochromatic light of frequency , the stopping potential for the photocurrent is . When the surface is illuminated by monochromatic light of frequency , the stopping potential is . The threshold frequency for photoelectric emission is
(Main 2019, 12 Jan II)
(a)
(b)
(c)
(d)
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Solution:
- Relation between stopping potential and incident light’s frequency is
. where, is the stopping potential and is the the work function of the photosensitive surface.
So, from given data, we have,
and
Subtracting Eqs. (i) from (ii), we have
Substituting this in Eq. (i), we get
If threshold frequency is