Key photoelectric facts for same wavelength

For photoelectric effect:

• The stopping potential depends on the maximum kinetic energy of emitted electrons.
• For a given metal and same wavelength of incident light, the photon energy is same, so the maximum kinetic energy is same.
• Therefore, the stopping potential is same for both intensities.

Mathematically, $K_{\max}=h\nu-\phi$ and $eV_0=K_{\max}$ Since $\nu$ is same, $V_0$ is same.

Effect of intensity

Intensity affects the number of photoelectrons emitted per second, hence it affects the photoelectric current.

• Higher intensity $I_2$ gives larger saturation current than lower intensity $I_1$.
• So the $I$ vs $V$ graph for $I_2$ must lie above that for $I_1$ in saturation region.

Required graph features

Thus the correct graph must show:

• Same stopping potential for both intensities
• Different saturation currents, with $I_{\text{sat}}(I_2) > I_{\text{sat}}(I_1)$

Conclusion

The figure satisfying these conditions is Option C.

Comparison with stored answer

Stored correct answer = C

Our derived answer = C

Hence, the answers agree.