Question

Light of wavelength $\lambda$ falls on a metal having work function hc/${\lambda }_0$. The photoelectric effect will take place only if:

• A. $\lambda \ge {\lambda }_0$
• B. $\lambda \ge 2{\lambda }_0$
• C. $\lambda \le {\lambda }_0$
• D. $\lambda \le {\lambda }_0/2$

Answer 1

Answer: (C)

$\lambda \le {\lambda }_0$

For photoelectric effect to take place, $E_{light}\ge W$ or $\therefore \frac{hc}{\lambda }\ge \frac{hc}{{\lambda }_0}$