Question:
Two identical photocathodes receive the light of frequencies $f_{1}$ and $f_{2}$ respectively. If the velocities of the photo-electrons coming out are $v_{1}$ and $v_{2}$ respectively, then
Correct Option: 1
Solution:
(1) $\frac{1}{2} \mathrm{mv}_{1}^{2}=\mathrm{hf}_{1}-\phi$
$\frac{1}{2} \mathrm{mv}_{2}^{2}=\mathrm{hf}_{2}-\phi$
$v_{1}^{2}-v_{2}^{2}=\frac{2 h}{m}\left(f_{1}-f_{2}\right)$