Question
When a metallic surface is illuminated with radiation of wavelength 
, the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2 
, the stopping potential is V/4. The threshold wavelength for the metallic surface is,
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-
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3
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4
Solution
C.
3
When a metallic surface is illuminated with radiation of wavelength 
, the stopping potential is V.
Photoelectric equation can be written as,
... (i)
Now, when the same surface is illuminated with radiation of wavelength 2
, the stopping potential is V/4. So, photoelectric equation can be written as,
From equations (i) and (ii), we get
