The metallic surface is illuminated with monochromatic light of wavelength 
, stopping potential for photoelectric current is 
. When the same metallic surface is illuminated with a light of wavelength 
, the stopping potentials is 
. What is the threshold wavelength for the surface?
A
B
C
D
Text Solution
Verified by ExpertsThe correct answer is:
A
Given:
For wavelength 
, stopping potential 
For wavelength 
, stopping potential 
Use Einstein's photoelectric equation:
For 
For 
Subtract the two equations:
Put this value back into the 
equation:
Substitute 
:
Divide by 
:
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