The work functions of Silver and Sodium are $4.6 \mathrm{eV}$ and $2.3 \mathrm{eV}$ respectively. Find the ratio of the slope of stopping potential versus frequency plot for Silver to that of Sodium.

Stopping potential $V=\frac{hf}{e}-\frac{{\varphi }_0}{e}$   (f=frequency)

Slope of V versus f plot $=\frac{h}{e}$

It is the same for both metals and independent of work function ${\phi }_0$.

Hence ratio of slopes for the two metals $=1$.