RE-NEET 2026 Physics Photoelectric Effect MCQ Question

The principle of the photoelectric effect states that electrons are emitted from a material only when the incident light has a wavelength shorter than the threshold wavelength of that material.

For cell 1, since $\lambda_1 < \lambda$, it will emit electrons, resulting in a stopping potential $V_1 > 0$. For cell 2, $\lambda_2 > \lambda$, so it cannot emit electrons, leading to $V_2 = 0$. For cell 3, $\lambda_3 >> \lambda$, it also cannot emit electrons, giving $V_3 = 0$.

Thus, the only viable option is D: $V_1 = 0$ (incorrect), $V_2 < V_3$ (both are zero). The tempting wrong options fail because they misinterpret the conditions under which electrons are emitted.