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
$\mathrm{v}_{1}$ and $\mathrm{v}_{2}$ respectively, then
Correct Option: 1
Solution:
(1)
$\frac{1}{2} \mathrm{mv}_{1}^{2}=\mathrm{hf}_{1}-\phi$
$\frac{1}{2} \mathrm{mv}_{2}^{2}=\mathrm{hf}_{2}-\phi$
$\mathrm{v}_{1}^{2}-\mathrm{v}_{2}^{2}=\frac{2 \mathrm{~h}}{\mathrm{~m}}\left(\mathrm{f}_{1}-\mathrm{f}_{2}\right)$