Q. Threshold wavelength for photoelectric effect on sodium is $5000\ \mathring{\mathrm{A}}.$ Its work function is
A) $15\ J$
B) $16 \times 10^{- 14}J$
C) $4 \times 10^{- 19}J$
D) $4 \times 10^{- 81}J$
Explanation
(c) $W_{0} = \frac{hc}{\lambda_{0}} = \frac{6.625 \times 10^{- 34} \times 3 \times 10^{8}}{5000 \times 10^{- 10}}J = 4 \times 10^{- 19}J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.