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When light of wavelength 248 nm strikes a metal, the stopping…
Question
When light of wavelength 248 nm strikes a metal, the stopping potential is V0. When light of wavelength 124 nm strikes the same metal, the stopping potential is exactly 3*V0. Using hc = 1240 eV*nm, determine the work function phi of the metal in eV, and report the integer value of 100*phi.
✓ Verified answer: 250checked by our engine — not a guess
Step-by-step solution
Einstein's equation: eV_stop = hc/lambda - phi (energies in eV). For 248 nm: KE1 = 1240/248 - phi = 5 - phi = V0. For 124 nm: KE2 = 1240/124 - phi = 10 - phi = 3*V0. Substituting V0 = 5 - phi into the second: 10 - phi = 3(5 - phi) = 15 - 3phi, so 2phi = 5, phi = 2.5 eV. Therefore 100*phi = 250.
Final answer250
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