Q. The work function of a substance is $4.0\ eV.$ The longest wavelength of light that can cause photoelectron emission from this substance is approximately
A) $540\ nm$
B) $400\ nm$
C) $310\ nm$
D) $220\ nm$
Explanation
(c) $\lambda_{0} = \frac{hc}{W_{0}} = \frac{12400}{4} = 3100\mathring{\mathrm{A}} = 310\ nm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.