A photoelectric surface is illuminated successively by monochromatic light of wavelengths λ and λ/2. Kinetic energy in second case is 3 times the first. Find work function.
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A photoelectric surface is illuminated successively by monochromatic light of wavelengths λ and λ/2. Kinetic energy in second case is 3 times the first. Find work function.

G1 Physics · Accepted Answer

Let initial kinetic energy K = hc/λ − W. In the second case K′ = 2hc/λ − W = 3K. Therefore 2hc/λ − W = 3hc/λ − 3W, giving 2W = hc/λ, so W = hc/(2λ). Answer: A.