When a certain metal was irradiated with light of frequency $1.6\times 10^{16}Hz$,the photoelectrons emitted had twice the kinetic energy as did photoelectrons emitted when the same metal was irradiated with light of frequency $1.0\times 10^{16}$Hz.Calculate $V_0$(threshold frequency) for the metal.

Question

$\begin{array}{1 1}(a)\;3\times 10^{15}Hz&(b)\;4\times 10^{10}Hz\\(c)\;4\times 10^{15}Hz&(d)\;2\times 10^{15}Hz\end{array}$