Question

Threshold wavelength of a metal is \(4000\ \text{Å}\). If light of wavelength \(3000\ \text{Å}\) irradiates the surface, the maximum kinetic energy of photoelectron is

• A. \(1.7\ \text{eV}\)
• B. \(1.6\ \text{eV}\)
• C. \(1.5\ \text{eV}\)
• D. \(1.0\ \text{eV}\)

Hint:

\(hc = 1240\ \text{eV·nm}\) is a useful constant. Here, \(K_{\text{max}} = 1240\left(\frac{1}{300} - \frac{1}{400}\right) = 1240 \times \frac{1}{1200} \approx 1.03\ \text{eV}\).

Answer 1

The Correct Option is D