A sodium surface is illuminated with light of wavelength 0.300 μm. The work function for sodium is 2
Source: JAMB · 2023
A sodium surface is illuminated with light of wavelength 0.300 μm. The work function for sodium is 2.46 eV. Calculate the maximum kinetic energy of the ejected photoelectrons for sodium.
[c = 3 x 10⁸ ms⁻¹, 1 eV = 1.6 x 10⁻¹⁹ J, h = 6.63 x 10⁻³⁴ Js]
Explanation
Photon energy E = hc/λ = (6.63 × 10⁻³⁴ × 3 × 10⁸) ÷ (3 × 10⁻⁷) = 6.63 × 10⁻¹⁹ J.
Divide by 1.6 × 10⁻¹⁹ to get eV: 4.14 eV.
Maximum kinetic energy = photon energy − work function = 4.14 − 2.46 = 1.68 eV.
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