Question

Up to what potential V can a zinc ball (work function $3.74eV$) removed from other bodies be charged by irradiating it with light of $\lambda =200nm$?

• A. $2.5V$
• B. $1.8V$
• C. $2.2V$
• D. $3V$

Answer 1

The correct option is A $2.5V$

Actually the required potential will be the stopping potential $\left(V_0\right)$. From the Einstein's equation photoelectric , $e{V}_0=\frac{hc}{\lambda }-W$

So, $(1.6\times {10}^{-19})V_0=\frac{6.62\times {10}^{-34}\times 3\times {10}^8}{200\times {10}^{-9}}-(3.74\times \times 1.6\times {10}^{-19})$ [use $(1eV=1.6\times {10}^{-19})$]

or $V_0=2.5V$