OnlineCBT
Physics · PYQ NEET UG 2026
हिन्दीA ray of light with wavelength \( \lambda \) is incident on three different photoelectric cells namely 1, 2 and 3. The threshold wavelength of these photoelectric cells are \( \lambda_1 \), \( \lambda_2 \), and \( \lambda_3 \), respectively and the magnitude of stopping potentials of these cells are \( V_1 \), \( V_2 \) and \( V_3 \), respectively. The relation between \( \lambda \) and threshold wavelengths are \( \lambda_1 < \lambda \), \( \lambda_2 > \lambda \) and \( \lambda_3 \gg \lambda \). The correct option is :
Correct answer · Option 3
\( V_1 > V_2, V_3 = 0 \)
Explanation
Photoemission occurs only when \( \lambda < \lambda_0 \). For cell 1, \( \lambda_1 < \lambda \implies \lambda > \lambda_1 \), so no photoemission occurs (\( V_1 = 0 \)). For cells 2 and 3, photoemission occurs since \( \lambda_2 > \lambda \) and \( \lambda_3 \gg \lambda \). The stopping potential is given by \( eV = \frac{hc}{\lambda} - \frac{hc}{\lambda_0} \). Thus, as \( \lambda_0 \) increases, stopping potential increases. Since \( \lambda_3 \gg \lambda_2 \), \( V_3 > V_2 \). Also \( V_1 = 0 \), hence \( V_1 > V_2, V_3 = 0 \) is correct.
