Bright red light ( ) of high intensity is incident on a clean potassium surface but…
PHYSICS · Subjective · A Level · Physics · Particles and radiation · Particles and radiation
Problem
Bright red light (λ=700nm) of high intensity is incident on a clean potassium surface but no photoelectrons are emitted, whereas a much weaker violet light (λ=420nm) produces a measurable photocurrent. Explain this observation.