Two identical photocathodes receive light of frequencies $f_{1}$ and $f_{2}$. If the velocities of the photo electrons (of mass $m$) coming out are respectively $\mathrm{v}_{1}$ and $\mathrm{v}_{2}$, then (1) $v_{1}^{2} - v_{2}^{2} = \frac{2h}{m}\left(f_{1} - f_{2}\right)$ (2) $v_{1} + v_{2} = \left[\frac{2h}{m}\left(f_{1} + f_{2}\right)\right]^{1/2}$ (3) $v_{1}^{2} + v_{2}^{2} = \frac{2h}{m}\left(f_{1} + f_{2}\right)$ (4) $\mathrm{v}_{1} - \mathrm{v}_{2} = \left[\frac{2h}{\mathrm{~m}}\left(\mathrm{f}_{1} - \mathrm{f}_{2}\right)\right]^{1/2}$
Two identical photocathodes receive light of frequencies $f_{1}$ and $f_{2}$. If the velocities of the photo electrons (of mass $m$) coming out are respectively $\mathrm{v}_{1}$ and $\mathrm{v}_{2}$, then\\
(1) $v_{1}^{2} - v_{2}^{2} = \frac{2h}{m}\left(f_{1} - f_{2}\right)$\\
(2) $v_{1} + v_{2} = \left[\frac{2h}{m}\left(f_{1} + f_{2}\right)\right]^{1/2}$\\
(3) $v_{1}^{2} + v_{2}^{2} = \frac{2h}{m}\left(f_{1} + f_{2}\right)$\\
(4) $\mathrm{v}_{1} - \mathrm{v}_{2} = \left[\frac{2h}{\mathrm{~m}}\left(\mathrm{f}_{1} - \mathrm{f}_{2}\right)\right]^{1/2}$