Question

Sodium and copper have work functions 2.3eV and 4.5eV respectively. Then the ratio of their threshold wavelengths is nearest to

• A. 1 : 2
• B. 4 : 1
• C. 2 : 1
• D. 1 : 4

Answer 1

The correct option is C

2 : 1

$W_0\propto \frac{1}{\lambda }\Rightarrow \frac{{\lambda }_1}{{\lambda }_2}=\frac{(W_0{)}_2}{(W_0{)}_1}=\frac{4.5}{2.3}=\frac{2}{1}$