A silver ball is suspendend by a string in a vacuum chamber and ultraviolet light of wavelength 200 nm is directed at it. What electrical potential will the ball acquire as a result of it, if work function of silver is `4.7 eV` ? `[h=6.6xx10^(-34)` J-s and `c=3xx10^(8) m//sec]`

Explanation

Energy of photon `E= (1242)/(lambda(nm))eV =(1242)/(200)=6.2 eV`
`E =phi + K_(max)`
`6.2 = 4.7 + K_(max) implies K_(max) =1.5 eV =eV_(s)`
Stopping potential `V_(s) =1.5 V`
The electron will be ejected until potential of sphere equals stopping potential
`V = V_(s) = 1.5 V`