According to Moseley’s Law, the ratio of the slope of graph between $\sqrt{v}$ and z (here v  and z are frequency of radiation and atomic number respectively) for $K_{\beta }$ and $K_{\alpha }$ is given  by $\frac{n^{\frac{3}{2}}}{\sqrt{2}}$ . n is equal to (Assume screening constant for $K_{\beta }$ is same as$K_{\alpha }$ )