Question

Light of wavelength $\lambda$, falls on metal having work function hc/${\lambda }_0$. 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

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

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

This will ensure that the energy of the incident photon is greater than or equal to the work function of the metal. The work function is equal to the ionization energy of metal. It is the energy required to remove an electron from the metal. The photoelectric effect is observed due to these ionised electrons

Hence, the correct option is $C$