The threshold wavelength of a metal surface is 500 nm. V is the maximum velocity of photo electrons when the wavelength of incident light is 400 nm. If the maximum velocity of photo electrons from the same metal surface is 2V, the wavelength of incident light is

see full answer

Talk to JEE/NEET 2025 Toppers - Learn What Actually Works!

Real Strategies. Real People. Real Success Stories - Just 1 call away

An Intiative by Sri Chaitanya

350 nm

300 nm

250 nm

200 nm

answer is C.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

$\begin{array}{l} \frac{1}{2} m V^{2} = h c (\frac{1}{λ} - \frac{1}{λ_{0}}) \\ \begin{array}{l} {(\frac{V_{1}}{V_{2}})}^{2} = \frac{(\frac{1}{λ_{1}} - \frac{1}{λ_{0}})}{(\frac{1}{λ_{2}} - \frac{1}{λ_{0}})} \\ {(\frac{1}{2})}^{2} = \frac{(\frac{1}{400} - \frac{1}{500})}{(\frac{1}{λ_{2}} - \frac{1}{500})} \\ \frac{1}{λ_{2}} = \frac{1}{100} - \frac{3}{500} \\ λ_{2} = 250 nm \end{array} \end{array}$