Question

The work function of a metal M is 6.3 eV. The wavelength of the incident radiation required to just eject the electrons from its surface (in nm) is:

• A. 102
• B. 330
• C. 197
• D. 310

Hint:

Use the relation \(E = \frac{hc}{\lambda}\) to find the threshold wavelength for photoemission. Remember to convert eV to joules when using SI units.

Answer 1

The Correct Option is C

Step 1: Use the eV-nm shortcut.
For threshold wavelength: \(\lambda_0 = \frac{1240}{W_0(\text{eV})}\) nm.

Step 2: Substitute work function.
\(\lambda_0 = \frac{1240}{6.3} \approx 197\) nm.
\[ \boxed{197 \text{ nm}} \]