Light of wavelength `400nm` is incident continuously on a Cesium ball. (work function `1.9eV`). The maximum potential to which the ball will be charged is

Options

A. 3.1V
B. 1.2 V
C. zero
D. infinite

Explanation

(B) `eV_(s) =(hc)/(lambda)-phi=(1240(nm)eV)/(400(nm))-1.9 eV=1.2 eV`
`implies V_(s)=1.2 V`
`:.` The cesuim ball can be charged to a maximum potential of 1.2 V