What is the work function of the metal if the light of wavelength 4000λ generates photo electrons of velocity 6 × 10^5 ms^-1 from it?
Answer: 2.1 eV
Explanation
To find the work function, we need to calculate the energy of the photon (E) and the kinetic energy of the electron (KE), then use the equation:
φ = E - KE
E = hc / λ = 1240 eV nm / 4000 nm = 3.1 eV
KE = (1/2)mv^2 ≈ (1/2) × 9.11 × 10^-31 kg × (6 × 10^5 m/s)^2 ≈ 1.64 × 10^-19 J ≈ 1.024 eV
φ = 3.1 eV - 1.024 eV ≈ 2.076 eV ≈ 2.1 eV
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