Question

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

Answer 1

Answer: (C)

310 nm

Answer 2

By using $\lambda_{0} = \frac{12375}{W_{0}(eV)}$ ⇒ $\lambda_{0} = \frac{12375}{4}$= 3093.7 Å

$\widetilde{–}310nm$