Dual Nature Of Matter Question 5
Question 5 - 2024 (30 Jan Shift 1)
The work function of a substance is $3.0 \mathrm{eV}$. The longest wavelength of light that can cause the emission of photoelectrons from this substance is approximately:
(1) $215 \mathrm{~nm}$
(2) $414 \mathrm{~nm}$
(3) $400 \mathrm{~nm}$
(4) $200 \mathrm{~nm}$
Show Answer
Answer: (2)
Solution:
For P.E.E. : $\lambda \leq \frac{h c}{W_{e}}$
$\lambda \leq \frac{1240 \mathrm{~nm}-\mathrm{eV}}{3 \mathrm{eV}}$
$\lambda \leq 413.33 \mathrm{~nm}$
$\lambda_{\max } \approx 414 \mathrm{~nm}$ for P.E.E.
