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

Answer

`7`

Explanation

`R=1cm`
`f=4.7 cm`
`(hc)/(lambda)=phi+eV`
`(1240(ev)(nm))/(200(nm))=4.7(eV)+eV`
`(1240)(200)e=4.7e+eV`
`6.2-4.7=V :. V=1.5` volt
`(1)/(4pi in_(0))(Q)/(R )=1.5`
`(9xx10^(9))(Ne)/((1)/(100))=1.5`

`9xx10^(11)Ne =1.5 , " "N=(1.5)/(9xx10^(11)xx1.6xx10^(-19))=(15)/(16)xx(1)/(9)xx10^(8)`
`=(5)/(3xx16)xx10^(8)=(50)/(48)xx10^(7)`
`:. Z=7`