Question

The minimum energy required to remove an electron from sodium atom is $3.313 \times 10^{-19}J$. What is the maximum wavelength of radiation that will eject photoelectron from sodium metal? ($h = 6.626 \times 10^{-34}Js$)

• A. $400\,nm$
• B. $500\,nm$
• C. $700\,nm$
• D. $200\,nm$
• E. $600\,nm$

Hint:

Maximum wavelength corresponds to minimum energy (work function).

Answer 1

Answer: (E)

Concept:
• Threshold wavelength: \[ \lambda = \frac{hc}{\phi} \]

Step 1: Substitute values
\[ \lambda = \frac{6.626\times10^{-34} \times 3\times10^8}{3.313\times10^{-19}} \]

Step 2: Simplify
\[ \approx 6 \times 10^{-7}m = 600\,nm \] Final Conclusion:
Option (E)