When a metallic surface is illuminated with radiation of wavelength λ, the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2λ, the stopping potential is \(\frac { V }{ 4 }\). The threshold wavelength for the metallic surface is ………. .
A. 4λ
B. 5λ
C. \(\frac { 5 }{ 2 }\) λ
D. 3λ
Answer:D
When a metallic surface is illuminated with radiation of wavelength λ, the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2λ, the stopping potential is \(\frac { V }{ 4 }\). The threshold wavelength for the metallic surface is ………. .
A. 4λ B. 5λ C. \(\frac { 5 }{ 2 }\) λ D. 3λ