Threshold frequency of a metal is 6 × 10¹⁴ s^-1. The kinetic energy of an electron emitted when a radiation of frequency 10¹⁵ s^-1 hits the metal is

 $\mathrm{K}.\mathrm{E} \mathrm{of} \mathrm{photo} \mathrm{electrons} :$

$$\begin{gathered} \mathrm{K}.{\mathrm{E}}_{\max }=\mathrm{h}(\mathrm{v}-\mathrm{v}º) \\ =6.625 \times {10}^{-34} \mathrm{J}.\mathrm{s}({10}^{15}{\mathrm{s}}^{-1} - 6 \times {10}^{14} {\mathrm{s}}^{-1}) \\ =6.625 \times {10}^{-34}\mathrm{J}.\mathrm{s}(10 \times {10}^{14} {\mathrm{s}}^{-1} - 6 \times {10}^{14}{\mathrm{s}}^{-1}) \\ =6.625 \times {10}^{-34}\times 4\times {10}^{14} \mathrm{J} \\ =2.65\times {10}^{-19}\mathrm{J} \end{gathered}$$