Question

A light of wavelength $\lambda$ falls on a metal having work function $W=hc/{\lambda }_0$. 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. $\lambda \ge {\lambda }_0/2$

Answer 1

The correct option is C $\lambda \le {\lambda }_0$

Photoelectric effect will take place only if the threshold frequency of the metal is less than the frequency of the incident light. In other words, photoelectric effect will take place only if the threshold wavelength is greater than the wavelength of the incident light.