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The work function for caesium atom is 1.9 eV. Calculation (a) the threshold wavelength and (b) the threshold frequency of the radiation. If the caesium element is irradiation with a wavelength 500 nm, calculate the kinetic energy and the velocity of the ejected photo electron. |
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Answer» (a) Work function, ϕ0 = 1.9 eV = 1.9 x 1.6 x 10-19 J λ0 = {6.6 x 10-34 Js x 3 x 108 m/s}/{1.9 x 1.6 x 10-19 J} = 652 nm (b) ϕ = hv0 v0 = ϕ/h = {1.9 x 1.6 x 10-19}/{6.63 x 10-34} = 4.598 x 14 s-1 |
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