Effect of frequency of incident light on stopping potential

What this figure shows. A graph with collecting-electrode potential along the horizontal axis (again split into a positive/saturation region and a negative/retarding region) and photocurrent along the vertical axis, this time showing three curves for three different frequencies $\nu_1<\nu_2<\nu_3$ of incident light at a fixed intensity. All three curves reach the same saturation-current plateau on the positive side (since intensity, not frequency, controls the saturation level), but they now cross zero at three progressively more negative stopping potentials $-V_{01}$, $-V_{02}$, $-V_{03}$ as the frequency increases from $\nu_1$ to $\nu_3$ -- the direct graphical demonstration that a higher-frequency radiation ejects photoelectrons with a higher maximum kinetic energy, requiring a larger retarding po …

What this figure shows. A graph with frequency of incident radiation along the horizontal axis and stopping potential along the vertical axis, showing two separate straight lines, one for Metal A and one for Metal B, each line rising linearly once the frequency crosses that particular metal's own threshold frequency ($\nu_{0A}$ or $\nu_{0B}$ respectively) and remaining at zero stopping potential for any frequency below that threshold. The two lines are drawn parallel to each other but offset horizontally, since different metals have different threshold frequencies (a property of the metal's work function) even though the slope of stopping potential against frequency -- which turns out to be the same universal constant, Planck's constant divided by the electronic charge -- is identical for every metal, foreshadowing Einstein's …