JEE Main 2025 Physics question
The work functions of cesium (Cs) and lithium (Li) metals are 1.9 eV and 2.5 eV, respectively. If we incident a light of wavelength 550 nm on these two metal surface, then photo-electric effect is possible for the case of
Answer: (2)
Solution
E = 1240/550 ≈ 2.25 eV. This exceeds Cs work function (1.9 eV) but not Li (2.5 eV). So only Cs shows photoelectric effect.