Question

Light of wavelength $4000\stackrel{\circ }{A}$ is incident on a sodium surface for which the threshold wave length of photo – electrons is $5420\stackrel{\circ }{A}$. The work function of sodium is

• A. 4.58 eV
• B. 2.29 eV
• C. 1.14 eV
• D. 0.57 eV

Answer 1

The correct option is B

2.29 eV

$W_0=\frac{12375}{{\lambda }_0\left(\stackrel{\circ }{A}\right)}=\frac{12375}{5420}=2.28eV$