OnlineCBT
Physics · PYQ NEET UG 2016(1)
हिन्दीWhen a metallic surface is illuminated with radiation of wavelength \( \lambda \), the stopping potential is \( V \). If the same surface is illuminated with radiation of wavelength \( 2\lambda \), the stopping potential is \( \frac{V}{4} \). The threshold wavelength for the metallic surface is
Correct answer · Option 2
\( 3\lambda \)
Explanation
Using Einstein's photoelectric equation \( eV = \frac{hc}{\lambda} - \frac{hc}{\lambda_0} \) for both cases and solving gives \( \lambda_0 = 3\lambda \).
