Practice question
Question
The kinetic energy of a photoelectron is 3.0 × 10⁻¹⁹ J when irradiated with light of frequency 8.0 × 10¹⁴ Hz. What is the threshold frequency of the metal? (h = 6.626 × 10⁻³⁴ J s)
Explanation
E = hν ≈ 5.301×10⁻¹⁹ J. W₀ = E - KE ≈ 2.301×10⁻¹⁹ J. ν₀ = W₀/h ≈ 3.47×10¹⁴ Hz.