A silver of radius `1 cm` and work function `4.7 eV` is suspended from an insulating thread in freepace it is under continuous illumination of `200 nm` wavelength light AS photoelectron are emitted the sphere gas charged and acquired a potential . The maximum number of photoelectron emitted from the sphere is `A xx 10^(e) (where 1lt A lt 10)` The value of `z` is
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Stopping potential `= (1)/(e ) [(hc)/(lambda) - phi]` where `hc = 1240 eV - nm` `= (1)/(e ) [(1240)/(200) - 4.7] = ((1)/€ [6.2 - 4.7]` `= (1)/€ xx 1.5 eV = 1.5 eV` `But V = (1)/(4 pi s_(0)) (q)/® = (1)/(4 pi s_(0)) (ne)/®` `:. N = (Vr(4 pi s_(0)))/(e) = (1.5 xx 10^(-2))/(9 xx 10^(9) xx 1.6 xx 10^(-19))` Compering it with `A xx 10^(2)` we get `z= 7`
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