For potassium metal, the work function $\phi$ (the minimum energy needed to eject an electron from the metal surface) is 3.68 * 10¯¹⁹ J. Which is the longest wavelength of the following which could excite photoelectrons? A) 550. nm B) 500. nm C) 450. nm D) 400. nm E) 350. nm

Question

Quizplus · Accepted Answer

The energy of a photon is given by $E = \frac{hc}{\lambda}$. To eject an electron, the photon energy must be at least equal to the work function. For $\phi = 3.68 \times 10^{-19}$ J, the longest wavelength $\lambda$ is calculated using $\lambda = \frac{hc}{\phi}$. This gives approximately 540 nm, so 500 nm is the longest wavelength from the given options that can excite photoelectrons.

For Potassium Metal, the Work Function ϕ\phiϕ (The Minimum Energy Needed to Eject an Electron from the Needed

For Potassium Metal, the Work Function $\phi$ (The Minimum Energy Needed to Eject an Electron from the Needed