Wavelength is changed from \(4000 \mathring A\) to \(3000 \mathring A\)
\(\frac{h c}{\lambda_1}= KE _{\max }+w_0\)
\(\frac{h c}{\lambda_2}= KE _{\max (2)}+w_0\)
\(\frac{h c}{\lambda_1}-\frac{h c}{\lambda_2}= KE _{\max }- KE _{\max (2)}\)
\(\frac{h c}{\lambda_1}-\frac{h c}{\lambda_2}= eV\)
\(\left(\frac{h c}{\lambda_1}-\frac{h c}{\lambda_2}\right) \times \frac{1}{e}=V\)
\(V=1.03 \,V\)