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A light of wavelengt `1240Å` falls on a metallic sphere of radius 1 m and work function `W_(0) = 3eV` . The maximum number of electron left from the sphere till photoelectric effest stops will be- (approximately)A. `5xx10^(6)`B. `5 xx 10^(7)`C. `5 xx 10^(9)`D. `5 xx 10^(12)` |
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Answer» Correct Answer - 3 Photoelectric effect stop when `V_("stop") =(K"ne")/(R)` from photo electric `eq^(n)` `(hc)/(lambda) - W_(0) =1//2 mV_("max")^(2)` `(hc)/(lambda) - W_(0) = eV_("stop")` `(hc)/(lambda) - W_(0) = c (K("ne"))/(R)` `therefore n= ((hc)/(lambda) - W_(0))` `(R)/(Ke^(2))` `=((12400)/(1240)-3)xx (1.6 xx 10^(-19))/((1.6 xx 10^(-19))^(2)) xx (1)/(9xx 10^(9))` `= 5 xx 10^(9)` |
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