Light of frequency f = 8.0 x 10^14 Hz strikes a metal surface with work function Phi = 2.0 eV. What is the maximum kinetic energy of the emitted photoelectrons? (Planck's constant h = 4.14 x 10^-15 eV s)
Answer and explanation
Correct answer: C. 1.31 eV
- Step 1: Einstein's photoelectric equation: K_max = h f - Phi. Step 2. Photon energy: E = h f = (4.14 x 10^-15 eV s) (8.0 x 10^14 s^-1) = 3.312 eV. Step 3. K_max = 3.312 eV - 2.0 eV = 1.312 eV = 1.31 eV. Answer: 1.31 eV. Why not the others:* 3.31 eV is photon energy without subtracting work function; 5.31 eV adds work function.
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