Question

The work function for two metals are 9eV and 4.5eV. Find the approx. difference between their threshold wavelength. (use hc = 1240 eV - nm)

• A. 138 nm
• B. 130 nm
• C. 112 nm
• D. 145 nm

Answer 1

Answer: (A)

138 nm

Answer 2

The correct option is (A): 138 nm

$\Delta \lambda=[\frac{1240}{4.5}-\frac{1240}{9}]$nm

= 138 nm